I installed Fallout 3 GOTY the other night and began having random crash issues right away. After three days of trying multiple things, I came across an article on the Win 7 forums (http://www.sevenforums.com/gaming/20199-fallout-3-windows-7-w-quad-core.html). Their recommendation worked for me. (It was also mentioned in another article here http://www.gamesas.com/index.php?/topic/1218977-fallout-3-goty-freezing-steam-edition/ , but that's buried a bit, so I started this separate topic)

Basically, Fallout 3 doesn't seem to like processors with more than 2 cores. So, if you have more, do the following to make Fallout 3 use only 2 of your cores.


From the Win 7 forum:
"The game engine has some issues with processors that have more than 2 cores. You can force the game to only use two of them and it will stop the freezing. I haven't had it freeze once since I did this several days ago.
Open up the fallout.ini file in: My Documents\My Games\Fallout3
[Copy fallout.ini and put it somewhere safe in case you need the original again later]
Find the line:
bUseThreadedAI=0
change it to:
bUseThreadedAI=1
Add another line after it and insert:
iNumHWThreads=2
This will limit the game to 2 cores and prevent the engine bug from causing the game to freeze."

If this doesn't fix your crash problem, you have something else wrong with your system.

Good luck!

This has been a well documented fix since the games GOTY release.