Nyroca,

With Windows you can never be sure about nothing...
Windows it's like a wrong fairy tale, anything can happen in it (but always bad things).
It's not a bad idea to upgrade you video card drivers then.
I start to see that this is that kind of problems that you never know what caused it and how to fix it. So try all you can before reinstalling... or turn to Linux

Good luck!!!

Edit: Have you tried looking for system errors with Norton Systemworks for example?