Good point about the power, John. Another interesting experiment would be to go into the BIOS and set the boot order to try the hard drive first. If the machine is actually rebooting, it will just reboot from the hard drive and you won't get the error message.

I did have a Win 98SE machine with a spontaneous reboot problem once. Never quite did nail it down other than it being a power issue, but I converted the machine to Linux and never had it happen again. That might be a drastic move :)

I disagree about disabling ALL of the power settings, though. I never shut down CPU function, but I always let the hard drives shut off, as low grade drives (read: factory installed) tend to die under the constant activity. Not to mention the intermittent annoying noise every 2 minutes as the hard drive spins up and then spins down again.