Computer reboots itself

have a Compaq 6016us running windows XP home. I recently did a system restore from the recovery disks. Now the machine, when I shut it down using start, then click the "turn off" icon, will shut down normally. Then, after about 2-3 minutes, powers on by itself, and reboots back into windows. There are no error messages. I downloaded and installed any available bios updates from Compaq. Oddly, if I unplug the machine while it is powered off, and then plug it back in, it does not power back up on its own. Any ideas?

 

I checked the bios and it does not appear that there is wake up on lan entry.

 

Sounds like a problem with your household current. Modern PC's never truly power off, the motherboard is always recieveing some power, normally during boot the power supply recieves a "all good" signal from the motherboard before sending power to the rails. In your case, it sounds like some type of line interference from your household current is causeing the PS to interpret it as a "all good" signal from the mobo. If you can get a surge protector with EMI filtering you can check it. You could also try replacing the PS. Although just buying a surge protector with line filtering is most likely cheaper if your present PS is good.

Could be a florescent lamp or large appliance that's causeing the noise..

 

thanks I think your theory is sound. I'll try it and post later

 

A better surge protector did not correct the problem. I believe it is some kind of hardwarde issue with either the PS power on button dust, or whatever. going to try blowing out the duat etc. thanks for your help.