Years ago, I had a job in Freight Forwarding. It was my job to help prepare the documentation for my various clients exports to various middle east countries. Sometimes, I had to deliver the documentation personally to the relevant country's embassy in London (this was the one aspect of the job I liked, because I love exploring and I got paid to go to all sorts of areas I wouldn't normally visit).
To ensure that customs were notified of the shipments, we had to use a special computer system to enter the details, and print any relevant documentation. For this, we had an IBM AT, connected to both a dot matrix and daisywheel printer, a modem (it used this to upload details of our shipments to an HMRC computer) and a serial terminal. I can't remember the OS, but it was either Concurrant DOS or Multi User DOS.
We had strict rules on how long we needed to keep documentation on shipments (5 years, IIRC), but due to the time required to upload, we were asked by customs to keep the online records to the last year or two, which meant one of my boss's jobs was, on a friday afternoon, deleting any out of date shipment records. For Audit purposes, we still had the paperwork.
The system asked the user to enter the record number to delete. This is terrible UI design, and asking for trouble already. It did allow you to enter a range, which made things slightly easier. My boss had been happily deleting ranges of records for years, and was comfortable doing so. But he made a mistake. He entered the range backward. The software did not check for this, and couldn't cope with it. It happily started deleting everything. When the deletion (which normaly took a few seconds) was still going over 20 minutes later, he looked and realised what was happening. He immediately turned the computer off (there was no option to stop it or quit).
When we got it back up and running, he tasked me with replacing the missing records. They didn't have a backup, and he didn't want to request access to our records from HMRC, because doing so would have meant admitting to an error.
So, I spent the next 3 months knee deep in shipping paperwork, re-entering the details of all relavant shipments on the computer. The company didn't survive much longer, and ultimately I was rewarded with redundancy a few months later.