Random Freezing

I built this desktop a few days ago and now when using it I experience random freezing. At first i believed the freezing to be my DLink WDA 1320 because whenever i installed the drivers for it after a few minutes (or longer if i was lucky) the computer would freeze. If i did not install the drivers then it seemed to work. However, the other day i managed to do a windows update that had drivers for the card, and that seemed to solve my problem.

However, I still experience random instances of freezing (no mouse or keyboard control, ctrl alt del doesnt work) and I have to restart the computer. I cannot tell what's causing this because it doesnt seem to happen at any specific time or during any specific program.

Any insight into solving this would be greatly appreciated!

I use Vista 64 bit
4 gigs of ram (G.Skill)
ASUS M4A78T-E mobo
Corsair 650TX PSU
Radeon HD 4890 1GB
AMD Phenom II X4 955