"Fallout New Vegas came out before Windows 7 was released and wasn't designed to run with that Operating System, therefore we have not worked on a fix for issues."
There it is, in all it's patheticness. Look up release dates for the game versus the Operating System. I believe it is about a week apart. And Win 7 had been in Beta for over a year prior. So they designed it to run on Vista? Well that was smart, that system was amazingly stable?
Lastly, this may work for some. Here is what I do to run the game without issues. I have a Radeon based videocard. If I try to run Fallout through steam it crashes every time. But if I go to the first dropdown menu in steam and hit update videocard drivers which are already in queue, it takes 30 seconds to update and game runs flawlessly after every time. No idea why, but it works.