Game Freeze, Black Screen, White Screen

[Eiluned]

Hi, I have this issue recently where half of the time I play, The screen will freeze and then if I hit a mouse key, the whole screen will turn black and then if I hit a key again, it will turn white. This will persist from 30 seconds to 3 minutes or so and then the game will resume to normal. On good days, it will happen once or twice, but on bad days, it happens every 30 seconds or so and I have to abandon the game. Some times, the system acts just fine until I am in a party and entering a quest, and then it starts this behaviour.

I have Windows Vista 64 bit and run 2, 8800 gtx cards in SLI with a quad-core processor. I have ruled out the router as the issue and can only guess maybe the OS or CPU compatability? Aside from trying a complete reinstall, has anyone seen this phenomeena and does anyone have any advise?