Last night my M-I-L's computer just turned itself unexpectedly. I mean like someone pulled the plug on it. I thought maybe she popped a circuit breaker. Power to everything else was on, so turned the computer back on - booted up, gave me the message at bootup about unexpected shutdown, selected start windows normally, gets to the Windows XP loading screen (yeah, I know, she still uses a dial-up fax machine connected to a phone line), then turns off.

Next round, I select safe mode, the list of drivers loaded started scrolling by and then bloop - power off.

Third round - get the motherboard splash screen, bang on delete key to enter bios - goes right to the unexpected shutdown screen again. Hmmm....delete key doesn't work to enter bios, okaaayyy.....

Grab keyboard from my computer, hook it up - everything normal!

Her keyboard that predated the Windows XP she is still using finally shorted out, overloading the USB port and at first chance Windows would kill the power to the computer to prevent damage. Just posting this here for others' reference.