[XFX HD5670]Black screen/temporary freeze

[EliteGM]

My brother got an XFX HD 5670 for his PC, but now in any games he gets random freezes where the screen goes black for about a minute and then the game pops back up in the exact same state that it froze in.

A weird thing is that the AMBIENT sound of a certain game still plays on, meaning that there is no shooting audible but water or wind, just background sounds are audible.

His PCs' specs:
Intel Core2 Duo E6600 @ [stock] 2.4GHz
4 GB (2x1gb OCZ Platinum 800MHz + 2x1gb Kingston 667MHz) RAM
Windows 7 x64
Antec (I believe it's Antec) 420W PSU

Games that freeze:
CoD: Black Ops
CoD 4: Modern Warfare

Games tested so far:
CoD: Black Ops
CoD 4: Modern Warfare
League Of Legends

Temps are <60C stressed so that shouldn't be it.

I'm trying out windowed mode atm. See if that does anything :/

[MentaL]

[HoodyKid]

Best thing to do is to clear the current drivers with driver sweeper and try different drivers.
If this doesn't work it must be a hardware problem, send it to warranty.

[EliteGM]

Running in windowed mode seemed to have rid him of the issues...

EDIT:
Nope, no luck.
I have now found out that the drivers crash :/
I used DriverSweeper and installed the drivers that XFX specified for the product but still no luck with these.