Fallout 3 hangs after installaltion

A common problem that occurs and generally 80% of the time the cause is the Fallout.ini file. A good solution is to locate the folder (usually under ...My Documents\My Games\Fallout3) and delete the folder entirely. There is no danger of ruining the installation as the game recreates the folder after it does a scan of your video hardware the very next time you attempt to run it.

Hopefully, the detection and settings are now correct and the game will run. If you have any downloadable content (DLC's) installed or mods, they may need to be enabled and sorted in a particular order by use of a mod manager.

If this does not help you, try reinstalling the game.