Re: IBM PS/2
We had a problem in our uni lab of PS/2 motherboards dying. All at the same seat, which wasn't used by the same person, so this time it didn't seem to be user error.
Turns out someone had run a chair or something over the mouse cord and it was internally shorted. After a day or so, it would kill the motherboard.
I noticed there was a 90 degree kink in the cable and replaced the mouse, and then a week later noticed our semi-daily run of dead motherboards had ceased.
Remember the damned Model 80s that were so heavy they had a "two-man lift" warning sticker on them?