Can't load Bioshock!

When I try to load a saved game it freezes and I have to do alt ctl delete. I have been able to play it before but now I just can't load, and one more thing I have gotten a new videocard an GTS 8800 640 mb, can that have done anything? Before I had the video-card nividea 7800 GTX and then it work fine. Or can it be that something has happend to the save?

Any help is appreciated

Does it happen when you use a different save or start a new game.

It does work to start a new game but when you well shall enter rapture and there is some loading the same problem occurred. I have got the lastest driver so don't use that as a tip.