being having a problem with my mum pc this last week, every time she shuts it down, it turns off, but after 5-15secs, it powers up again, cant seam to find out the problem!! just for ref: its running Windows Vista Home Premium! Thanks in advance!!!
I can only think of 2 possible things. A sticky power switch or a corrupted registry entry in the shut down command. When did it start?if you know try restoring to a previous point. And check the on/off switch.
This is probably a hardware problem. Does it still fail to shutdown if you disconnect the power switch. if so, I'd suspect either the motherboard has gone stupid or there is a short between the 'power-on' pin and ground or the power supply has gone stupid and just turns on regardless of what the motherboard tells it to do.
I've seen it twice before on vista and once on XP. The restore worked on one occasion and on the other 2 it was a reinstall which fixed it. What can some times happen is that is that the power/sleep functions get messed up also check is not set to wake on usb activity like sleep mode.
Have you tried taking the Power Profile out of High Performance and putting it on energy saver? Could be the reason, though I'm not 100% sure...
i've seen this also - the computer is restarting not shutting down sorry couldnt be bothered looking for the cause re install and solved (ok not that great a reply)
Happened to me and took ages to work out - wireless usb mouse was waking the pc upon shutdown. Check BIOS and disable wake on usb. Least its worth a shot.
