From Mexico.purplecow.org
- Open up the fallout.ini file in: My Documents\My Games\Fallout3
- 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 the game still crashes try
iNumHWThreads=1