Are the X1950 drivers officially supported in Windows 7? I was having similar troubles with an X850 crashing in Windows 7 running various games. Black screen and Audio continuing, Sometimes i got a wierd stripes too. It was because the card wasnt officially supported, and the vista drivers that were offered caused problems, Which sucked.
I got the problem with most games though, not just one specific game. I take it you've gamed with more than just Bioshock 2?