Windows 7: Fallout 3 Black Load Startup Crash

I have recently upgraded from Windows Vista to Windows 7. After checking out the features, I decided to load up my (Steam) copy of Fallout 3. I clicked "PLAY" and a black screen appeared with the circular blue Windows load icon (see attached image) and waited for Fallout 3 to load. And waited. And waited. Eventually, I had to Ctrl-Alt-Delete out of Fallout 3.

I've tried everything I could think of: I restarted, I installed updates, I lowered my settings, I disabled my mods, and I ran Fallout 3 as an admin. I still get the same problem, and this has never happened to me before!