Jokeface

Hello everyone,
I've been using my computer for months now and was very happy with it, recently I've been getting lockups at least once a day random times, I am unsure of what is causing this, I have to hard restart/turnoff the PC, which can corrupt my system.

I run window updates often, so im sure it isnt drivers or anything plus installed every update ASUS had on their website for my motherboard. I also clean & defrag both of my hard disks often. Ran diagnostics on ram too, no problems found...

Specs are as follows:
My OS is Vista 32 Home premium SP1
Motherboard: ASUS P5KPL-VM
2GB of ram
Geforce 8600 GT
(anything missing?)

I think that the tutorial about restoring the User folders (my music, pictures etc) may have something to do with this, since I had problems the 1st time missing music and a duplicate picture folder. I used the manual regedit option which worked, only after 3 restarts with boot failures and an inactive graphics card, but it worked later on. It could be this.

Any Ideas? Could it be registry corruption?