Desktop shuts down and boots up again right away


May 3, 2015

I've been trying to solve a problem that my Dad has been having with his desktop computer. It seems that whenever he shuts it down, it will boot back up again right away.

Some things that we've ruled out: It's not software because this happened while he was running Windows XP, and we've since reformatted and installed Windows 8.1 and it still happens. It has also been happening before and after we replaced the power supply with a new one (which needed to be done anyway). We have also checked to make sure the power and reset buttons are plugged into the correct pins on the motherboard, according to the motherboard manual.

I thought it might be some kind of wake-on-LAN setting in the BIOS, but we live in different cities so I haven't been able to check anything in the BIOS yet.

Could this be a motherboard problem? Something else? I would appreciate any ideas.

Thank you.