You need to turn off the blur and the AA in the settings, and then it'll work.
This one is now because my housemate has 'fixed' the game with a high resolution patch and all I get is a black screen. Whoo!
If you don't start Dark Souls within the next few days I might just ban you.
I find myself more and more likely to NOT even start a game because I know it'll be too much of a time sink. I'm looking at you Fallout: NV, Dragon Age, Torchlight 2, Dark Souls.
Only joking, I'll give you until this time next week.