"Out of Cheese" Error
I was expecting a real mouse, chewing on the cables.
Welcome once again to On Call, The Register's ongoing chronicle of IT incidents that readers have managed to survive, divert or diminish, while emerging with reputations intact. This week, we meet a reader we'll call "Grant" who was summoned to a user’s desk to address an issue described as "My mouse pointer is twitching." …
On one of my policing gigs, visited a station that had a stables attached, complete with cat to control the inevitable mice. The cat got banned from one office after he threw a furball up on one of the Sergeants - the consequence of that was the mice promptly invaded it and caused absolute havoc with everything from cables to the occupants' lunches. After many cables had been replaced and users freaked out, the Sergeant was told to swallow his pride and let the cat back in - it solved the problem, though there was further angst when one furry corpse was concealed under a radiator in mid-winter.
Our acreage belongs to the (mostly feral) cats, but they share it with us in return for fresh water, a place to sleep away from the coyotes, and a little quality chow. They also share with the folks east, west, and south of us (all of whom understand cats). The cats pee and poop at the outer corners of the ranch, where it won't get in anybody's way ... and in the fancy rose garden and pool area of the asshole who lives just north of us. He hates cats, and they carefully return the favo(u)r ...
The idiot to the north is clueless. And has had a serious rodent problem for the couple decades that he has lived there ... Strangely enough, we don't, and neither do the neighbors to the east, west and south. I wonder why.
 Most of them get trapped at least once for spay/neuter and basic injections (difficult or impossible to live trap a feral cat more than once) ... According to the vet, they probably titer out for things like rabies for as long as they live, which isn't long. Sad to say, the ferals are part of the food chain here in Northern California.
The BBC iPlayer*** is currently showing a repeat of a 2014 three part study into the behaviour of cats. Their study group was large - and divided into three environments: town, village, and farm. One difference was that farmyard cats were more sociable with each other than domestic cats. The latter were very territorial and easily stressed by competitors. Possibly as they were rarely from the same lineage - whereas farmyard cats were usually related.
***Probably geographic limited access.
had it been, I'd have recounted the tale of my Picanto, which kept misfiring and occasionally ground to a halt.
No amount of diagnostic checks showed any specific cause for the problem, and the garage wanted to change expensive parts for trial and error.
I went back to basics and checked the air filter - to discover that a field mouse had come in from the cold and chewed the air filter into fairly small pieces [supplemented bt bits of paper and cardboard from the garage floor]. These scraps were being injected directly into the cylinders!
Checking the air filter would have been one of my first actions. It's easy to do (most times, unless you have a BMW diesel in a Rover or Freelander - honestly, they should have re-designed the M47R air filter so it was not at the back of the engine bay).
When diagnosing performance problems, go through everything that is cheap and easy before even involving a garage.
I was issued a monstrosity of a wireless keyboard to complement my wireless trackball and mouse (which I use simultaneously thank you very much). Since it took twice the square footage of my old keyboard I stuck it in a drawer. Every few months I'd put something that rolled in that drawer, of course never remembering straightaway...
I've yet to see a wireless keyboard that takes batteries.
Really? I don't think I have had any wireless keyboards that did not take batteries. Most have been Logitech, some some random cheapies, none have been rechargeable (unless you buy rechargeable batteries yourself). Mice on the other hand I've had both ones that take batteries and ones that have built-in rechargeable.
"you're left with a perfectly good but useless keyboard in 5 months when the "rechargeable" batteries die."
I'm not following this. Not only do I infrequently see wireless keyboards with rechargeable batteries, but when I do, they last a lot longer than five months because you can recharge them. What are you doing that causes them to die so quickly? Is there something wrong with the recharging system? I'd be surprised if you had to recharge more than once a month for those, and the only one like that that I've used lasted about three months before needing a recharge.
Has anyone invented a wireless mouse where the ball* acts as a dynamo, recharging the mouse?
*Ok, ok, yes I'm old.
Another idea is putting solar cells on the mouse to recharge the battery. Obv somewhere on the mouse which doesn't get covered up when the user uses it. Ok, maybe not such a 'bright' idea.
Being old I remember sunlight causing big problems with mice not working due to it interfering.
Logitech K800 - of which I have two, and they are lovely keyboards. Shame about the G915 I got a couple of years ago :(
Anyway, long story short, the second of these was bought from Amazon Germany but with a UK keyboard layout. I suspect it had been in the warehouse a while as when it arrived the batteries were dead. There seemed to be a little screw cover (no seal or anything) covering a compartment, so I unscrewed it and found 2 AA rechargeable batteries from a well known decent brand.
I raised a ticket with Logitech asking if they could send a couple of new batteries to replace the old non-functional ones, and was told that they were "not user replaceable" and I should send the entire keyboard back....
Bit annoying but I wasn't going to arse around doing that so I sourced some myself and it's been just fine ever since.
Worth trying anyway. But did you have to get German rechargeable batteries or did UK ones do? ;-)
I have been caught out with batteries and chargers being NiCd (old, bad) or NiMH compatible, an issue that mainly went away when I forgot about that and I killed most of my NiCd batteries in a NiMH charger :-(
I've got a very flat Bluetooth keyboard by - good heavens, "Polaroid", I think it means Asda (British end of Walmart, or it was) - that I use just to log in a tablet basically. I don't turn it off as such, but evidently it goes to sleep and doesn't need recharging for several weeks.
I have to admit, that has caught me out on my own PC in the past.
As time goes by, for various reasons (best known to myself), I change keyboards. And one time I had a wireless one which I then switched for another. I can't remember if the replacement was a wireless or wired one (it doesn't matter anyway), but what I do remember in hindsight is that I left the batteries in the old wireless one as I 'stored it'. And I didn't remove the dongle.
Or in other words, put it down the side of somewhere where if anything else were ever also stored there, it was likely to cause keys to be pressed.
And something did.
It drove me nuts trying to figure that one out having forgotten about the stored wireless one. Naturally, the presses on the stored keyboard were intermittent just to make it harder to figure out.
One time I was swapping keyboards for my workstation at a particularly... unorganized helpdesk job, which entailed pulling one of the Logitech wireless boards from a drawer and putting in some new batteries. My coworker two cubes down was very confused when his computer started typing all on its own.
Stop me if you've heard this one...
We had a small sister company, that didn't have an IT department, who's MD tended to do things without asking*. On one occasion he decided he and the FD needed wireless mice and went out and bought them from his usual supplier (Dixons - it was a while ago!)
As usual he then wasn't happy and expected us to sort the problem for him so I rocked up there on my next trip up to the area. Apparently his mouse pointer kept moving randomly, and the FD was having the same issue. Now this was many years ago before wireless mice used encoded signals and effectively their two desks were back-to-back with just a flimsy stud partition wall between. Can you see where this is going?
Two mice running on the same channel (and no option to change it) a few inches apart was always going to be a recipe for disaster. The MD kept his, the FD went back to his cable mouse and normal service resumed.
*Another one was to buy a Sony Vaio laptop from Dixons, against company standards. Just over a year later a windows update overwrote a driver and effectively bricked it (IIRC the display reverted to EGA 16 Colours). Did he have the original install disk(s)? No. Was the driver available from Sony? No. Did Dixons want to help? No. It turned out the laptop was a DSG parts bin special directly from Sony Japan. Sony UK weren't responsible, Sony Japan referred it back to DSG, Dixons said it was out of warranty so not their problem. His "I've saved money over the corporate deal" ended up costing another new laptop.
Of course the MD knows better than anyone (because he's the MD^) how to do stuff, had the lappy continued to work (out of pure luck*) then his money saving idea would have been extended to everyone else thus proving his superior level of genius.
^Many MDs are expert at 'something', the smart ones know when they've stepped away from that.
*The few Vaio I've seen had very delicate keyboards that fall apart far too easily.
I had several Vaio laptops back in the 90’s and noughties - they were solid pieces of kit and never gave any significant problems - that is until Windows 8/10, as Sony had stopped support and no suitable video drivers were available for the update. A 20yo Vaio continued in service until this year, running XP and connected to a projector in a local church (offline and just needed to run the PowerPoint viewer); it was only replaced with a new laptop because internet access was starting to be needed. I also had a 15yo Vaio still running as a loan m/c until last year (dual boot Windows Vista and Ubuntu). A third Vaio was also retired last year - running a 32bit Linux for its final 5years and retired because its battery decided to inflate (hastily removed). I could still get a replacement battery but the easing of C-19 restrictions has reduced my need for loan kit.
Overall, I found Vaio’s solid and reliable kit. I’m on Macs nowadays and find them to be similarly solid and reliable. Of course, others are free to disagree.
Watch out for the MacBook Pros: https://www.theregister.com/2022/08/15/ncat_flexgate_apple_macbook/
All my computers are older than 4 years; my TRS80 model 100 (1983) only bit the dust a couple years ago, until then I was using it to generate lunch menus for the kids. I've been surprisingly happy with last decade's Latitudes for price:longevity, my 2015 7250 runs fine despite looking somewhat worse for wear.
I second the opinion on old Latitudes, I'm writing this on E7240 that is on its second screen. Replacement batteries are aplenty, just as well as they tend to have lot shorter lifespan than originals. Want to carry a spare anyway as run time is not always that brilliant. Nice 12.5" FHD screen (sadly the FHD version is glossy touch screen), fairly lite. Has built-in 3G etc so perfect for on the go.
Also at least so far Dell is nice enough to keep drivers and their own additional bits downloadable for probably all the way back (haven't looked past D620/625 as those are the oldest I have in use at the moment.
My preference for laptops is Dell as they seem content to keep drivers available until the heat death of the universe. I have a couple of 2014 M4800s which, probably due to their brick outhouse build quality, are still running beautifully. One on Win10 (needed for Fusion360) and the other on Mint. Bought as refurbs for about the same cost as a chromebook.
Typing this on an E6430 that's been fully maxed out over the years, it's my workhorse machine and I've got a couple of them. Easy to work on, well designed, cheap parts and lots of availability, only problem is that stupid 'texture' coating on the keyboard surround that so many manufacturers were using back then, which did NOT last. I had a couple of D series machines and they were just as easy to work on but the versions with the quadro graphics chips had a problem where the chip would roast itself and melt its own internal connections, no matter how much cooling you put on it.
I keep a C600 around (PIII/866, 512MB RAM & ATI Mobility Rage128 with 8MB of dedicated video ram. Real beast) to run Windows 98 programs, been reliable for twenty years now. I may be swapping in an IDE->M2 adapter and drive soon.
I have a stock of Dell E6410 running W7, W10, and Linux Mint. Those commercial laptops had much more rugged cases than their domestic ones - even without the ATG enhancement. My only problem has been that it seems impossible to remove the screen bezel without breaking its retaining lugs.
Another problem is when loaned to people whose slim laptop has broken - they fall in love with it and it is never returned.
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Jesus wept! Getting any sort of complaint resolved at Dixons was an exercise in futility. Or any semblance of customer service for that matter. The company's reputation was so shit, the management imagined rebranding to Pissy World would be an improvement. It didn't. They're still shit. And how bad does your reputation have to be that moving to Pissy World would be a step up?
Anyways, serves the mug who bought the dodgy Vaio right. He should have bought the extended warranty.
Pissy Whirled have the distinction of having their supply contract with a large university cancelled - mid contract - for underperformance
They're the _only_ IT supplier to have ever had this happen. Despite the woeful performance of some of the others they were in a league of their own
Many years ago, I was in a PC world just to pass the time (the only things I ever bought there were normally on the discount table) and I overheard one of their 'experts' talking in glowing terms about something wirelessly, possibly a wireless range extender, to some hapless customer, and talking absolute bollocks. I really felt like jumping in and correcting him, but I resisted the urge.
Another time I was wanting a wireless access point in a hurry (and this was early days of WiFi before Amazon sold everything), and another of the 'experts' tried to suggest that if I bought one of their expensive all-in-one ADSL routers, I could eliminate the current ADSL only router, my software firewall PC, and the old access point that I had and could still be secure, because 'the new router's firewall will be far better'.
He only shut up when I pointed out that I worked for a large well known company, with responsibility for their Internet security, and almost certainly knew more about the capabilities of 'firewalls' than he did. I never like pulling the 'I work in this field' card, but in this case, I felt I just had to.
I bought a Vaio from Dixons/PCW many moons ago and was offered 'extended warranty'... despite there being a clear label on a display announcing free extended (5 year?) warranty just by mailing back a postcard... and the salesdroid couldn't understand why I turned down their offer of paying extra
And don't get me started on AO... bought a washing machine and a fridge from them online and within the hour I had received a call from their favoured warranty company offering an extension that a quick mental calculation said I could replace either item within 18mo and both within 30mo. When I pointed this out, along with the fact that the old washer was at least 15y/o and the fridge possibly 30+, the salesdroid said that things aren't designed to last that long now, to which my response was along the lines of "so you're saying that you're selling crap!"
(I'd already done a little due diligence and picked brands that were more reliable than 'well known' brands that are still trading based on historic 'reliability', despite this plainly being very historic)
Had a work colleague in the office recently and his Logitech wireless mouse wouldn't connect to his laptop at all. He'd spent a good while switching the channel using the button on the base of the mouse, removing and reinserting the USB dongle and a couple of reboots but it still wouldn't work. I suggested - and this was a complete stab in the dark - to try pressing the channel button on the mouse in and holding it in for a few seconds. It worked. The mouse reset, was picked up by the USB dongle, connected and worked fine. My thinking was if you can momentarily press the button to switch channels, would a long press force a reset, similar to how a PC power switch works these days.
When wireless mice first came out. Except they only had two channels, so if more than two people were using them, everyone's equipment quickly becamse useless.
And for a joke, when you were bored, you'd just change the channel on your mouse and move it around a lot and wait for the cries of surprise and annoyance from your colleagues.
Even better were the keyboards. Change the channel, and type something like "This is IT, your account has been suspended for watching too much porn"
PCs weren't the only ones affected by touchy peripheral ports. Back in the day, I worked on a project that used Silicon Graphics Onyxes. This refrigerator-sized beast had a custom SGI keyboard connector which was protected by a small fuse inside the computer.
The client's sysadmin for some reason chose to unplug the keyboard and blew the fuse when the plug was reinserted. This system was still under development, but was already running some live content on a major cable television network in the US. Given the continued work on the software, some actual console interaction was necessary.
This of course happened on a Friday afternoon, so the SGI rep was not amused at having an own-goal impinge on his weekend.
From an electrical POV it was because the power for the PS/2 port was very limited (sometimes thru the keyboard controller chip) and hot swapping would instantly connect the capacitor in the connected device across the power rails, looking to the chip like a dead short, for a few ms. Many chipsets didn't handle that well, the most common was to simply power down the port and refuse to work till rebooted
Slightly worrying that he didn't think to check if there was owt plugged in at any time but instead had to rely on device manager
Seems a lot of people working in IT seem to start at a high level and word down rather than starting at the lowest level and working up. It's basic diagnostic procedure to start with physical checks.
Well, my war story is about serial connections. Now IT Can Be Told (TM). When working for a leading effects/animation house in Soho we had some very tasty SGI systems for effects. One was a state of the art SGI 3000 systems, running some important software and costing $$$. One day I decided I needed a serial console on this machine.
Merrily fetch an RS@#@ cable and plug my laptop into the serial port.. then... sound of running feet as many engineers rush into the machine room. What the fsck is going on? The effects machine is down.
Turns out there was some process started at boot time which hung onto the serial port - the act of actually connecting something to the serial port brought the system down.
I don't think I ever figured out what process this was.
Many years ago we had a Sun server acting as a remote serial console for an Alteon load balancer (don't ask). All fine, apart from when we had to reboot the Sun for patching, the LB unexpectedly rebooted in unison - taking down our busy website while it rebooted. Apparently the Sun sent some special control sequence down the line, it took us a while to work it out!
Sun SPARC escapes to PROM monitor on receipt of BREAK.
Break on serial connection is holding TxD positive for a period of time. On a SPARC 9600bps console connection 4ms is enough for it to think a break was sent and drop to the PROM. This was almost guaranteed to happen if plugged into serial terminal that was then turned off or on (with most terminals if not necessarily all).
Had a colleague running a big computational job on a sun monster (48 cpus back when that was a lot). To prevent anyone from using that machine we'd disabled remote login for normal users and swapped the dual monitors ( gorgeous 21inchers) for a single 17inch one. Job was running for 3 weeks ( out of an estimated 5) when a colleague spilt coffee on his own keyboard.
And decided to swap it.
Long ago, and in another country, I was due to demonstrate our CAD program running on the newly announced Sun-2 (that's M68000 Sun-2, not Sparcstation 2). Waiting with tie fully up to collar while the journos were given a light presentation and drinks, then another presentation -- and drinks, then... I pulled out the keyboard connector. Sun crashed of course. So then there were a frantic few minutes while I rebooted it , fired up the CAD program and got the demo material back on the screen.
Later I was told I could have "plugged it back in, typed 'C' and the Sun would have recovered".
Back in 2018 when I'd started at a new place got a call from a user saying "words are being typed on my screen but mean nothing".
Went up and watch. Sure enough they were. Two of the keyboards in the office on same bank of desks had decided to interfere with each other.
I wonder if those aren't using Bluetooth after all. That's common on the cheap ones that built their own RF system because they often don't bother with any system to reject commands from other devices using the same channel, but that's part of the Bluetooth spec so anything that does use Bluetooth shouldn't accept packets from other devices. Those commands could cause problems with getting the real packets through if they're located too close together, but that would result in real keystrokes not being recognized, not incorrect ones. The downside to using proper Bluetooth keyboards is that they require the Bluetooth connection to be set up beforehand and if that's your only keyboard, it can be annoying to do it. I think that's why the USB dongle custom RF design is more common.
TP-link made two models of USB bluetooth adapter, the UB400 and UB500, which use the same MAC address for each model device.
These are little black adapters that plug into a computer and can be paired with whatever bluetooth keyboard and mouse you have.
You can have a UB-400 and a UB-500 in the same room, but not two UB-400's or 500's
Ah yes, that takes me back to a call in which diagnosing the problem took much less time than persuading the user to accept said diagnosis, and I was left with the irritating question of whether the ordeal would have been over quicker were my voice not obviously female.
It was shortly after my organisation had got serious about remote working, and everywhere desktops were being replaced with docking stations. I took a call from a user who said that his laptop had been behaving strangely since being plugged into the dock. It quickly became clear to me that it was receiving keyboard input from somewhere, yet the user swore the only visible keyboard was the laptop's own.
There followed something of a battle of wills. The user was convinced I was wrong, but I knew that I had to make certain there was no keyboard plugged into that dock before I escalated the ticket to the team that was allowed to actually go out and visit desks, or I risked wasting their time and looking like a fool. So I finally persuaded him to check the USB ports and follow the cables.
Lo and behold, there was a keyboard sat in a nearby In-tray with a load of papers resting on top of it. Problem solved. User slightly deflated.
"I was left with the irritating question of whether the ordeal would have been over quicker were my voice not obviously female."
I can see why you'd wonder, but tbh this doesn't seem like anything out of the ordinary for a support call. Some users are complete arseholes. I've had to tear a stripe off one or two, politely of course, because they were being obstructive to their colleagues - IT support are their colleagues - who were just trying to resolve the issues they'd reported. Usually they'd be good for a bit after that talk, but one cokehead salesman drove 50 miles, stormed into the building, and shouted himself out of a job.
Look, I've been doing this a while. I've dealt with the ones who were just as arrogant with my male colleagues, and with the ones with whom it was known - to everyone but them, usually - that they had a problem with women, or at least women in certain roles. It is a statistical certainty that I have had support calls that would have gone more smoothly had I been male-presenting. And I would like to be able to *mention the possibility* that this was one of them without some well-meaning individual popping up to inform me, with eye-watering condescension, that Some Users Are Arseholes and This Sounds Like A Normal Call.
Occam's Big Paisley Tie gets really, really tiresome.
So next time that sexist arsehole is being difficult, remind him about this incident (and any others where he was in the wrong in a similar way) and ask him if he would like you to report him for his very obvious sexist attitude.
Bonus points if you know (or can learn) his full names and use those.
(And make a recording of the call.)
If this helps, I've generally found female help desk people a lot more helpful than their male colleagues. So the misogynist users are actually losing out.
That said, I've been on both sides of the support desk at various times and I can confirm that Some Users Are Arseholes, regardless of pronouns.
The most spectacular sexist dickhead we had call once was answered by the team manager, who was female. He asked to speak to the manager of the team because in his dim view females couldn't be managers and he wanted to speak to somebody competent. He eventually got it through his skull that the female he was talking to was indeed the team manager and he then demanded to be put through to her manager. He was not happy when he found that the next manager up was also female and had been briefed on his prehistoric views on life.
"And I would like to be able to *mention the possibility* that this was one of them without some well-meaning individual popping up to inform me, with eye-watering condescension, that Some Users Are Arseholes and This Sounds Like A Normal Call."
I _thought_ I was saying that you needed to tweak the story a bit because the misogyny just wasn't coming across at all.
Having done IT support at the desk next to my wife, I'm well aware that some of the arseholes are misogynist arseholes.
"before I escalated the ticket to the team that was allowed to actually go out and visit desks"
I think I might have reminded him (irrespective of whether it was actually true) that a call-out would be charged against his teams budget so he might really like to double check.
"Grant visited the user, who moved the mouse pointer to a box – at which point it did indeed start to move despite no human hand upon the digital rodent!"
Dell laptop track/glide pads are (or used to be) notorious for this.
And why of why does every damn manufacturer keep shipping them with bloody tapping enabled?
If you get on with tapping fine... if you don't and, like me, find the bloody thing constantly misinterpreting my movements for tapping it is bloody dangerous. It is constantly selecting, dragging and dropping God knows what to God knows where until I can turn the stupid thing off....
I'd rather it was just turned off along with all other bloody "gestures" and left to those who like them to enable them - the option with the potential to do least damage.
For those, like me, for whom tapping and gestures don't work. It is not a matter of just not liking them. They are bloody DANGEROUS. For us it is like driving a car where every third time you put your foot on the brake it accelerates and every third time you turn the wheel left it lurches right. It is that bad.
Possibly a simple question durintg setup of "Do you want tapping/gestures?" and if you answer "No" they are killed, TOTALLY.
Dell - grrr.
On my latest laptop they deleted the three mouse buttons, the trackpad is the mouse.
Except there is no middle button! Cue much wailing and gnashing of teeth when using it to access xterm over VNC...
So - I eventually found out, there is a gesture to emulate middle button.
However Dell now operate their support forums on a "need to know" basis, and only send solutions by direct mail to users, lest the rest of humanity find out their secret sauce.
There are plenty of people asking about it, and no solutions. It took me literally months to find out how.
(tap three fingers on the trackpad...)
"I eventually found out, there is a gesture to emulate middle button."
On most PEE CEEs (including most laptops), hit both buttons at the same time. It's been that way since at least the late 1980s.
On many Linux distros, two fingers on the touch pad, click the left button.
For your distro, search on "<distro> three button emulation".
I once shared an office with a young chippy and the staff's resident crumudgeon. A likeable fellow, but a bit reactionary too.
I loaded the new & shiny PCAnywhere on his computer and set up a host session. Set it to auto-launch at boot too (Win98 days where everything needed a mid-day restart). Sitting across the office I would jiggle his mouse off the 'Okay' button when he targeted it. I would add extra characters when he was typing too.
Hilarity ensued, as he operated the PC slower & slower, trying to catch his mistakes when they happened. Hand waving and eloquent cursing whenever the unexpected happened. Myself and the young chippy were duly entertained for days until finally fessing up to the prank.
This was, of course, back in the days when people had a sense of humor. Today, such a prank would be a major InfoSec & HR violation.
In the days of DOS, I wrote a small TSR (terminate and stay resident) program that hooked the keyboard interrupt. It randomly replaced key presses with others, just adding or subtracting one from the scan code - the faster one typed, the more likely it was to hit. Typing slowly? No problem. Getting up to speed? Typos galore,
Hilarity ensued as nobody could figure out what was wrong.
Over the years I have acquired a large number of Byron 433mHz wireless door chime units***. They have two sound settings - "Westminster" and "Avon" - that are selected in each bell push. The house has a front door wired bell push and a back door wireless bell push. In addition there is a "visitor" infrared beam across the drive. Several chime units are distributed about the house and property.
An Arduino acts as as a spoofing bell push on activation of either of the two bell pushes or the beam interruption. The front door is then signalled with a Westminster chime sequence repeated five times; the back door with an Avon chime repeated five times; the beam uses the Avon chime but only repeated twice.
It was a dark and stormy night - "Ding Dong" - visitor or back door? Repeats several times - and keeps going. No one in sight at either door. Nor is there a wind blown piece of debris flapping across the beam.
Eventually switch off the Arduino unit - and the chimes continue. Must be the back door bell push signalling directly to the chime units. Get wet taking it apart and remove the battery - "Ding Dong" continues unabated. Am I being pranked?
Apply logic - what has changed recently? I tidied the garage earlier - which created a tall stack of plastic boxes. One of those is crammed full of the spare chime units and accessories. Dismantled the stack - and heavenly silence. A spare bell push - coded for Avon - had a live battery. It was in a plastic bubble pack which had gradually become squashed by the compression of the box lid by the higher boxes.
It actually happened again a few years later. This time the box was stored in the garden shed - and there was another live bell push that had been overlooked. It took no time at all to guess what was happening.
***I never threw the Byron mains plug chime units away when they started to fail with discordant low volume - just bought some more off ebay. Recently I found that the X2 mains-dropping capacitor needed replacing in them - having deteriorated to a fraction of its nominal capacitance.
A customer had a really cheap wireless keyboard that would reppeeaatt keys as it typed. Worked fine on another system though.
Turned out, the keyboard had already been replaced with the same but there were 2 receivers plugged in.
Hopefully no offices bought a bunch of these...
Twice, many years ago, I was called out to fix a mouse pointer that would move to where it was told, but then jumped back to its original position.
The cause? Each time, buried under piles of paperwork on the desk was a Wacom tablet with the stylus left lying on it...
Many years ago, before I retired, I was working on a project in an outpost in Stevenage. The local IT helpdesk was in the same building, so they could (and did) visit users' desks when needed. They also ran a display wall, back at base, where the least intelligent calls were displayed for posterity.
One such was a call from a user who said that his/her mouse was almost completely unresponsive. A visit to the user's desk elicited the following facts:
 the mouse in question was a promotional mouse from some IT show or other;
 the mouse in question was made entirely out of plastic foam, with no electrical functionality whatsoever;
 the only reason that the user observed any response at all was that sometimes in moving the promotional mouse, the user had accidentally bumped the desk, causing the real mouse to move at random.