I got Left 4 Dead today and when I load up a level the screen is black and I can see items etc.

I've tried changing the settings from high to low in the video section, the brightness is fine so I have no idea what's wrong >=[
I'm pretty sure my GFX card is updated so that's about it, anyone know the problem? Sorry I'm kinda vague

Oh and this image is green because it's green when my settings are high and black when they're low.