Probs with DoD Source

i am tryin to play DoD Source on my pc and everytime i start it the screen looks like it will play but then the screen goes black, although I can still hear the background music and I can hear the mouse click. I have been able to play this before but now it doesnt seem to want to play. Of course when i try to start the game it says my video card is unsupported, but I still play it like normal with no problems until recently. Any help?