WCH wrote:
> I've been running a Windows 2000 installation for at least a year. It's
> fully patched and updated. I run NIS (also fully updated) and WinFax
> all the time (FYI). The PC (a fast AMD with 512 MB of RAM) runs all the
> time.
>
> Starting this week I'll come in the room and find the machine off. Just
> shut down. Or I'll come in and find that it's rebooted and is waiting
> for the password prompt for a network connection. In both cases,
> something has caused this PC to shut down/reboot. I'm never in the room
> when it happens. I have no idea what's going on. I haven't installed
> any new software lately. I don't think it's an electrical power
> fluctuation, in that it's on a UPS and I brought in a bigger UPS to
> replace the other one, just in case. No help. The PC will shut
> down/reboot two or three times each day now. I'd hate like hell to have
> to do a clean install, as I've got a ton of stuff on here and it'd take
> hours to reinstall. And even then, how do I know that'd solve the
> problem?
>
> How should I proceed to diagnose this issue? I don't even know where to
> start.
> TIA -- WC
It's been awhile since I've used a windows box, but I would start by
checking your power settings in the control panel. They might be set to
power down the machine after a certain amount of time with no activity.
Windows had a tendency to 'adjust' itself on me at times. So it may have
done this for you.

Next running anti-virus software is not always enough. Do a full system
scan.
Also try running a spyware/adware remover. Adaware I hear is good.
Check your Powersupply and make sure that the fan is still running. My wifes
box had this problem and it just over heated and shutdown.
Finally pending others advice, do a complete system backup incase this is a
hardware problem.
Good luck,
JesterDev