-- PLEASE DONT TRY THIS UNTIL SOMEONE ELSE CAN CONFIRM IT --
I found after a similar problem, when my PC was working better then, that i went to My Computer properties, removed the graphics card from the hardware list, Windows autodetected it, and installed it's 'own' drivers. Back then I was having probs with other games, and it sorted most of them out.
Like I say, dont try this yet until someone else can confirm whether this is a method you should try. My PC seems to have a mind of it's own, so anything goes.
Hope its some help