Timed shutdown problem

[Lazyletters]

I have one PC on our Admin network that automatically shuts down every night at 6pm. It is the only one that does it, it has not been told to do it, the power settings are 'always on', the server is not telling it to shut down. There are no timed updates set on it either. So why is it shutting down? Why do I want it to stop, the person using it is the head and she is often here after 6pm! When it shuts down, it does it suddenly and does not object if she restarts it immediately.
I've searched the MS site and found nothing. PC is running XP Pro SP2 and Server is 2003 standard SP2, if anyone can help I would be grateful.
Denise

[JamesC]

Have you checked scheduled tasks to see if there is something shutting it down at 6pm there?

How about checking the event log to see if anything is mentioned about what could be shutting it down?

[Lazyletters]

I checked the scheduled tasks and nothing is set except the A/V and spyware.

I checked the event log last time but I think I might give that another look, but nothing showed up last time and it's doing it every day.

Thanks for the suggestions though.

[ICT_GUY]

Does it shutdown or does it switch itself off?

[strawberry]

have a look in the bios.

[altecsole]

Type AT at the command prompt and see if there are any entries.

[bizzel]

Perhaps it's a script that runs at logon and shuts down after a number of hours? Check the startup folder and the Run section of the registry for both HKCU and HKLM.

Also, give us a list of running processes in case something in there relates to it.

[enjay]

Is it shutting down cleanly or does it just suddenly go off? If the latter, I'm wondering if the power feed momentarily drops out at that time for some reason - that would cause the PC to turn off and, depending on BIOS settings, restart again. See if the PC always turns off even if you move it to your office and whether "normal" PCs continue to act as expected when in that location.