Another nice one that happened to me went as follows.
User calls, wailing that he's just lost the Word document he has been working on. He just switched to his internet browser, and Word was gone. Now, I'm the developer of an unrelated program and I'm not paid to do general support, but I wanted to establish a good relationship with the customer, so what the hell.
I login via remote control software and take a look around; sure enough, there's no trace of the document. Word doesn't seem to have crashed, either. It starts fine, and doesn't prompt to recover a crashed document.
I ask the user to show me what he'd been doing.
He types some stuff into Word, then, lightning-quick, he moves his mouse to the top-right corner, clicks on the red "X", moves his mouse to the "quit without saving?" dialog, clicks YES, and then opens the browser.
I tell him: "You... you have just quit Word without saving".
He says "No, I haven't".
"You literally just... look, could you please do it another time?"
This time, when he's about to click YES, I use the remote control software to smack the mouse cursor away. I force him to read the dialog box.
"That's not what happened before!"
I told him that I couldn't help him further as my job isn't tech support, so sorry, and hung up with as much courtesy as I could muster. I honestly have no idea what you're supposed to do in a case like that.