This is not a question, I just want to share my expirience - who knows - maybe somebody Google's it out, and then find it usefull...
A week ago (or a few days more) I've had a problem with my computer: it was restarting all of the sudden without any message, without any warning, and without any specific action done on it prior to that symptom - randomly - just *snap*, and it restarts without apparent reason (absolutelly non what-so-ever).
First it was restarting ocasionally (for a period of time), then - in last few days it was restarting itself in about three to eight minutes after it starts to work, then it was resarting during loading of the operating system (Windows 98 SE), and then finally it was just rebooting and rebooting and rebooting indefinitely even before it displays anything on the screen. At last there was some buzzing sound - like something is choaking the power-supply fan. I took it to the repairman. (monitor (connected to that power supply) doesn't turn on neither)
I told him that I think it's about the power supply, and I was right (fan works, the electricity itself was making the buzzing sound).
So - if your computer has such (or exact) symptoms (persistant random unprovoked rebooting/restarting) - don't wait until the power-supply burns your motherboard (or - god forbid: a hard-drive) - turn it off, unplug it and: off to the rapairman... (if you will...)
(of course have in mind that maybe something else is wrong with your computer, even though the symptoms are identical (such as motherboard problem) - nevertheless: think of all the potential consequences of the smoldering power supply...)