My PC comes back on after I shut it down

For the last couple of months, my PC restarts, even when I select Shutdown from the options. I turn it off manually when it does that. Tonight when I came home from being out for dinner, my PC was on, and there was a notification that MS had installed updates. I know with 100% certainty it was off when I left.

Do those bas***** at MS have a way to turn on my PC remotely? Is there something someone has put on my PC to keep me from shutting it off? I have run two anti-virus programs and a spyware program and none of them found anything.

Thoughts from the experts please

Might want to check your network adapter settings in device manager. I've heard of this before... I think yours might have something checked or selected that could keep your computer from shutting down... the exact words escape me right now, but it's something along the lines of "allow this device to keep computer on" I think.

Doesn't appear to be the issue.

Did you ensure that there are no "wake on" settings enabled in BIOS?

The only other thing I can think of, is that your motherboard could be damaged. Hopefully that's not the case.

I have no idea how to look at BIOS or what to look for.