Have a HD 4850 (brand unknown) on a 939 motherboard, running windows xp pro. 430 watt psu. For the past week, video is always perfect during post, bios, windows intro. After xp desktop loads, I'll get dots, artifacts, and inability to play 3d game. Warm reboot won't help. But if I turn machine off, and then on again, problem goes away, and I can 3d game indefinitely without problem. CCC says my temp is OK (79-80 C immediately after exiting intense 3d game). I think problem went a way for a few days when I ran defrag. Any ideas. Drivers are latest.
Try uninstalling the VGA driver s , and then Run DriverSweeper to delete any remaining files , re install latest driver , if u have oced ur card , go back to stock . if the problem persist then i'm afraid ur vga is faulty