1.) Try the patch. Fallout: Welcome to the Official Site

2.) In the proprieties of both FalloutLauncher and Fallout3 exe, DISABLE visual theme, and set the apps to ADMINISTRATOR.

3.) Bethesda Website fix (disable ffdshow)

1. Click Start
2. Click “All Programs” (or just Programs, depending on the version of Windows, whether they’re using “classic,” etc.)
3. Go to the ffdshow folder.
4. Click “Audio decoder configuration.”
5. In the left hand pane, click “Info & debug.” This is the second entry in the list.
6. In the right hand pane, near the bottom, find a check box labelled “Don’t use ffdshow in:”
7. Check that box, and in the text box underneath (it lights up when you check the check box), add “fallout3.exe” (don’t include the quotes). If there is already something in that box, put a semi-colon ( ; ) after what’s already there, and fallout3.exe after that. Do NOT use spaces, since ffdshow will think that’s part of the filename. A valid entry would be “explorer.exe;fallout3.exe” (without quotes).
8. Finally, click “Ok” and start Fallout 3.

4.) Running windowed at 1680x1050

5.) Disable the sound driver.

6.) Uninstall ASUS GamerOSD and ASUS SmartDoctor.

7.) Make sure you are running the required system components.

• Windows XP/Vista
• 1GB system RAM (XP)/ 2GB system RAM (Vista)
• 2.4 Ghz Intel Pentium 4 or equivalent processor
• Minimum: Direct X 9.0c compliant video card with 256MB RAM (NVIDIA 6800 or better/ATI X850 or better) These are the only supported manufactures.

The only supported Video Card Chipsets:

• NVIDIA GeForce 200 series
• NVIDIA Geforce 9800 series
• NVIDIA Geforce 9600 series
• NVIDIA Geforce 8800 series
• NVIDIA Geforce 8600 series
• NVIDIA Geforce 8500 series
• NVIDIA Geforce 8400 series
• NVIDIA Geforce 7900 series
• NVIDIA Geforce 7800 series
• NVIDIA Geforce 7600 series
• NVIDIA Geforce 7300 series
• NVIDIA GeForce 6800 series
• ATI HD 4800 series
• ATI HD 4600 series
• ATI HD 3800 series
• ATI HD 3600 series
• ATI HD 3400 series
• ATI HD 2900 series
• ATI HD 2600 series
• ATI HD 2400 series
• ATI X1900 series
• ATI X1800 series
• ATI X1600 series
• ATI X1300 series
• ATI X850 series

8.) Try some of the Performance Tuning tips from There are several things you can do to increase game performance.

• Make sure you have no other programs running in the background.
• In the Fallout 3 Launcher, select OPTIONS:
  • Lower the Resolution
  • Turn Antialiasing OFF
  • Turn Anisotropic Filtering OFF
  • Set Detail settings to MEDIUM or LOW. Select Advanced for more detail options.
  • Turn all water options to LOW or OFF.
  • Set Screen Effects to NONE.
• While running the game, go to the SETTINGS menu and select DISPLAY.
  • Reduce the FADE distance sliders for Actor, Item, Object, Grass, Shadow, Light, Specularity, OBject LOD or Tree LOD

With that being said, there are a bunch of people having issues with this game and I do believe the manufacture is looking into this as well, but has yet to produce a patch that addresses these issues. The main comment seems to redundant, but "SAVE, SAVE, SAVE," just about before doing anything that changes the stage where you are.

Keep checking the manufactures website for more information.
Patch Thread #1
Patch Thread #2