How do I get Fallout3 to stop freezing?

I was playing "Mothership Zeta" and right when you get abducted, the aliens are probing me and then the game freezes. The alien in the back is still moving (He's swaying and blinking smoothly.) so I ume it's not compleatly frozen. (I have GOTY.) I've consulted PS home, which isn't working. And another detail. Whenever I press X my character grunts and there is a clanging sound. But nothings happening. Please help, I'm quite scared, I don't want to start over!!