Everytime I go to join a game on the server, the screen minimizes. When I pull it back up its grey and the graphics dont load. The screen is blue, however I can hear whats going on. When I start the game over it works sometimes. I dont understand whats going on. I have all updated drivers to all of my parts.

Specs:
Abit A8 pro pentium d 2.4
Nvidia 7950 gt oc'd
3 GB of Ram
Creative Labs xtreme gamer sound card
LG 19" widescreen monitor
steel sound 5h headphones
G5 mouse and Logitech Keyboard
Icemat
Tsunami case