Hopefully there will be a patch for it soon. BTW, my game froze too when I rode the elevator in the Washington Monument. I used to play with Vista as OS and I can't remember it ever crashing then. Since I upgraded to Windows 7 I also get the occasional freeze-up. I eventually had to fast travel from the top of it just to get out.

Froze twice in row right inside the door, three times in the elevator going up, and twice more in the elevator going down. Most recently it took me 15 minutes, a reboot, and probably 5 or 6 restarts of the game just to get to the top of the Washington Monument. Its pretty random though, sometimes it won't do it for hours or days and once in a while it will just keep doing it over and over again. I have the GOTY version of Fallout 3 on PC (through Steam, probably a mistake), and it is prone to freezing.