Computer keeps freezing

Hi, recently my computer has decided it would be funny to randomly freeze on me. There is no rhyme or reason to it. Doesn't matter if I've been listening to music, surfing the net, or just letting it sit there doing nothing (idle). It doesn't accure after a certain program is run or at any given time. It does however happen more frequently now than it has before. I also noticed that every time I attempt to update my video drivers it freezes. The screen goes blank (and if I were listening to something, it would take the last couple tones and repeat them, typical to freezing). Then a 'no input signal check cable' box pops up on my monitor. There are no noise changes or lights going out or fans shutting off on the tower (it appears as though the monitor just hibernated, but of course it doesn't). The only way out is to hit the reset button or hold the power button. I haven't loaded any new programs lately. A couple of my drivers are out of date (video card being one of them, but it won't stay un frozen long enough to download the new ones). I scan the drives with AVG (w/ updated definitions) and there are just a couple warnings, but no viruses. I am currently running XP Pro SP2 with all the latest MS updates. Oh, I thought it might have something to do with the heat (its been hot here in alabama lately) so I've been having a fan on and I pulled the heat sink off the processor and cleaned all the junk out of the fins (quite a bit actually), but that still didn't fix it. Please help because I am about to throw this $3000 hunk of junk in to the street.

Try running a chkdsk on your hard drive.

What kind of PSU do you have? Video card?

You can disable hibernation. Right click on desktop-->properties-->screen saver-->click 'power'-->hibernat tab-->uncheck box to enable hibernation.

Ok, turns out my original suspicion was right. It was an overheating issue. However, it wasn't my cpu like I was thinking. It was my video card. I went to pull it out and had to wait and let it cool because it was too hot to hold. Immediately I knew it was the issue. I tore it apart and blew out all the caked dust and junk, threw it back in and it's been running like a champ ever since. I also picked up a desk fan to assist with cooling for good measure.

Now to the questions:
I am running a Thermaltake 850w psu with a geforce 9800 gx2 video card as well as 4x 1gb sticks of corsair ddr2