What happens is after a while the game freezes in a kind of checker board effect and then goes to just a solid colour, freezing the whole computer up. It could happen as soon as I enter the game or 1-2 hours after.
I've re-installed windows, the game, drivers etc but nothings helped, and I know my computer is more than capable of running GW. Please note that I have no problems with other games.
Any advice would be great as I'd love to start playing again

PC Specs
AMD Phenom 9850 BE
MSI K9A2 Platinum
2x 2Gb Geil Black Dragon PC2-8500 1066Mhz
ATi Radeon HD4870
Cheers