Hi, this morning I was sleeping but I was almost half awake when suddenly something woke me up and I saw my PC booting up. I was quite shocked as nothing like that ever happened to me. How is this even possible? Is there reason to worry about my PC or about having poltergeist in the house?

Check the BIOS settings. There is a setting to have your PC boot up on its own at a specific time of the day, which should be in Power Management.

Ninja'd >_<

Mine boots from sleep mode every day to do a disc defrag. Freaked me out for a few days. Booting on from off-mode is, well, it brings to mind the etymology for booting: to pull oneself up by one's own bootstraps. Spooky stuff.

What comes to mind here is in the bios there is an option to reboot if power is lost. Occasionally this can boot your machine up from a power off state.

So you may have had a slight dip in power or a power cut for a few seconds, when the power has returned to normality the PC has booted itself up.

Its possessed

KILL IT... KILL IT WITH FIRE

Is it one of those new Polterputers?

It has become sentient!

This setting has never worked for me. :<

Thanks for replies. Thing is I have it in this setting for... hmm, since July I think, so 9 months and after figthing some troubles in first months I changed nothing in BIOSsince then so it is quite surprising it started now.
And I was all alone at home. There is no one taht could wake it. Maybe fly. :-)

My current machine can't do it either, for some reason or other. Might be that I'm using a USB keyboard now rather than a PS/2 one? I never investigated it, to be honest.

Do you have windows? I remember windows update woke up my pc in the nights. So you could check that on google.

H4x0rzzz!!!!