Had a user that every... 3 to 6 months, her pc would flat out die. Not just be odd, but mobo fried. Pop open the case to inspect and it was obvious something had blown. Replace mobo, reinstall, good to go. Using the same software as everyone else, not over clocked gaming hard, just regular PC. 3 months later, it'd pop again. Mobo blown.
Pop under desk, check power, seem ok. 2 machines into a splitter, but other machine ok, they're not too much draw, nothing else on that same socket.
Replace entire machine, maybe the psu faulty. 6 months later, blown Mobo.
What the heck is she doing to the machine, those woolly jumpers she wears and static or something?
Sheer fluke was sat opposite her one Friday afternoon working on someone else's machine and I hear 'rickitytickity' noises, like, power sparking. "Anyone hear that?" "hear what?" "that noise?" "no?" And to be fair, with the yelling going on in the office, printers/faxes blaring out, was fairly noisy for an office sometimes, especially the day before a sailing trying to get everything squared up. I pop under the desk to investigate the noise (that's my excuse and I'm sticking to it), and I notice the girl who blows machines up every few months, the power cable, under her feet, and she's rolling it back and forth out of habit I guess. So it's everso slightly twisting in the psu and that's what's blowing it up. One cable run cover later, problem never came back though she moaned that she liked rolling the cable, helped her think.