An outdated graphics card driver may also cause Fallout 3 to freeze in your PC. You have to update drivers for fixing this problem.
From where should I get an updated version of the graphics driver?
You can get the graphics driver from the website of the Graphics Card manufacturer. You must know the Serial Number before downloading an appropriate version.
An older version of DirectX results in Fallout 3 freezing problem. Download the latest version from the official website of Microsoft and install it on your computer.
Delete the Contents in your Game Cache
The game cache contains the most frequently used files for speeding up the game performance. Corrupted cache contents cause games in Windows 7 to freeze randomly. To fix the problem delete the cache contents.
1. Open Console. To do so, press ~ key
2. Type PCB and press ENTER.
Install the Latest Version of Microsoft.NET Framework
Installing the latest version of Microsoft.NET Framework may also fix Windows 7 game freezing.
1. Visit the official website of Microsoft.
2. Search for the download link of the latest version of Microsoft.NET Framework.