For some reason, when I woke up this morning, my computer wasn't logged on to my account. Instead, it was at the account select screen, and it said that some process could not be run.

So I logged on and for some reason, everything was slow. I checked my processes screen in task manager, and saw 2 processes which I did not recognize: dfrgfat.exe and defrag.exe. I most certaintly did not run either myself, but when I logged off, my computer turned off, and did not turn on again.

Can anyone give me a hand?

It's most likely a virus. What do you mean by "did not turn on again" . Does the fan still turn? Do you see a biosscreen? Or maybe perhaps even a Windowsscreen?
If you can still see windows trying to start, hit F8 and select ' safemode'. Scan your hd for virusses with AVG (free)

Regards Niek

Well I don't really know, but I don't think it even turns on at all, as in no boot noise, nothing.
I'll check the wiring when I get home, but I already did check for viruses and such with AVG. Are there two versions, one for spyware and one for viruses?

How did you check for virussen if you computer won't start?
Yes. Use AVG for visusses and adaware for spyware.

If your computer doesn't boot at all, it's probably your PSU (power supply unit). Try replacing that.

Regards Niek

Yeah, it's the power supply. Also, my hard disk fell out of its frame, so maybe that had something to do with it. Anyways, I'm getting it fixed at best buy (under warranty), so it's all good. Thanks for your help, though.