my friend i had the same problem. since i have 2 videocards and i recently updatet the drivers,for some reason the setting were set back to default.
I have nvidia gtx460m on my alienware.
first i dowloaded the direct x 11.0 and reinstaled it.
i opened nvidia control panel(right click on desktop) and changed the 3d settings from aplication chose to nvidia highperformance card.
im sorry for my bad english,its rather poor.
hope you understand what im trying to say.
and i hope it will work for you .
have a nice day.