Strange 4870 problem

I have just recently had a strange problem arise with my system that I think is graphic related. Has occurred in both games ( e.g. COD 4 and COD 5) and regular desktop to internet surfing. The problem is that my screen, any image, will go checkerboard and lock the system up. I have updated all mobo drivers and all Vista patches are current. I am using 8.12 Catalyst drivers and have tried rolling back to 8.11 as well. Still occurs in both. I have went back to stock cpu speeds, just had a mild OC to 2.9 gHZ but temps never got hot. Never OC'd the card at all.

My specs are:

Q9300 at 2.5 gHz
4 gigs of DDR2 1066 @ 5-5-5-15
Asus P5Q PRO MOBO
Sapphire 4870 video card
550 Antec psu
1 x 750 GB Seagate SATA HD
1 x 74 GB Raptor
Vista Business 32-bit

Everything was bought new at end of August 2008 except psu which was bought in Feb. Any ideas what may be causing this problem?

Hey similar problem here on a Force3D 4870 1 Gb, with hangs occuring in Far Cry 2 and Gears of War. Specs are:
Intel E 8400 cooled by ASUS Triton
Gigabyte P45
4 X 1 Gb Kingmax DDR3 1333
Gigabyte Odin Pro PSU 800 Wt
Force 3D 4870 1Gb
2 X 250 Gb RAID0 WD Caviar Black
2 X ASUS 20x DVD-RW
Gigbyte Isolo case
Catalyst 8.12-Vista 64
The card is damn hot if you keep the default fan speed but the problem persists even if it's increased and the temps are normal

Can it be a driver problem?

Try this mate:
http://www.warhammeralliance.com/f [...] p?t=118448

Good luck.

Thanks alot the two solutions look good. I'll try one or another.