Note: If the accessibility features got turned on because of the failing keyboard, the user is going to have to figure out how to turn them all off again.

Oh, third possibility: The user has one of those macro-capable keyboards and it got programmed with a macro.

The old Gateway Anykey keyboards were notorious for this. One accidental press of one of the keys on the keyboard (it happened to be an easy to hit key on the upper right corner), and you were instantly (and without warning) in Macro-Creation mode. Anything you typed after that was a macro. So for example, you would press the S key and it didn't do anything. So you'd pound on asdfjkl to see if they worked. They didn't. Well, what you didn't realize was that you just programmed the S key to play back a macro of asdfjkl. And now every time you press S...

Anyway, that *also* sounds like the symptoms. But hopefully this user doesn't have one of those kinds of keyboards, otherwise they would have already run into this problem *years* ago.