conjunctivitis arthritis

I bought DKS today from Steam and upon Installing it i started it to experience but Alas theres a serious problem to me. the characters and also the World generally speaking wont show, all i purchase can be a black screen however i can see the mini-map along with the windows tho ..... this is extremely weird! i attempted to play with all the various Video options but nothing works! i is able to see the Cinematics fine tho but just i start playing i cant understand the world in any respect. anyone got ideas what could be the problem? My video card is often a Geforce Gts 250 and i play under Vista 64x