Computer turns self on!?!?

Has anyone ever heard of anything like this before?
Last night I shut down my computer normally before going to bed. About 10 minutes later, I hear the fan start whirring, the case lights turn on, and the computer starts up completely on its own. I got up and shut it down again, and jumped back in bed. Not more than 5 minutes later, the computer booted up completely again.
Even though I have a router, I got a little paranoid and disconnected my cable modem after shutting it down again. It didn't start again the rest of the night.
The computer (self-assembled) is only a few weeks old, running XP. I've had no problems like this before with this or my previous computer. The only thing I've done to it in the past few days is install "Half-Life 2".
I asked a couple of "experts" in my office, neither of whom could even make a guess.
Would a power spike be capable of powering-up a computer? Any other ideas? Maybe an exorcism? ;-)

 

the only thing i can think of that resembles that situation is when a computer is put to sleep, with keyboard wake up off... the slightest mouse movement can revive it....but im sure u know its not in standby or hibernate

 

I'm pretty sure you can set certain motherboards to start up at a certain time in BIOS, and even started up with a keystroke

 

Maybe its a poltegeist....

 

It could be that your router is sending wake signals to your PC. Either that or someone/something on the net is doing it. But theres always a chance that its the dead communicating.....

 

A static electrical shock can certainly wake a PC up even when it's powered down. Are you in a static-prone area? Is your PC on a good power-conditioner or UPS? Did you ground your motherboard properly to the chassis? Is your floppy cable oriented backwards? Any of these things can cause the event you're describing, so I'd start there.

-AT

P.S. - Also, like Ninja Fetus described, many BIOSes have a feature where keyboard, network, and even mouse activity can send a "wake" message to your system. Make sure everything of that nature is disabled!

 

Thanks for the responses & ideas, everyone. I don't have a UPS or power massager, I'm probably going to go out looking for one in the next few days. Static is a possibility... I live in Iowa, the air here is very dry during winter.
The event in question did happen during a pretty harsh winter storm... electrical fluctuations certainly could have been possible at the time.
The dead making contact would be a great story to tell, but I'm thinking any of these other scenarios are more likely.

 

Well Steam updates automatically, so if "Wake on LAN" is enabled in the BIOS, maybe Steam has something to do with it.

When you turned it off the first time, it probably didn't have time to update completely so maybe that's why it restarted again, and why it stopped when you unplugged your modem.

 

you could have a faulty switch on ur case? post back Dave :good:

 

Probably not since it stopped after he unplugged his router.

 

whats the switch on his case got anything to do with his router????

 

Nothing at all. Addis what were you thinkin! If you have something to 'Wake' on in your BIOS it should be under power settings, power management or something along those lines. If you see anything that says wake on_____. Or anything of that nature that corresponds to a mouse, keyboard, LAN, time, you might wanna try toggling it.