If you’re having this issue, you are not alone. But there is a fix for this:

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.
Apparently the above solution also works sometimes if you freeze mid game either temporarily, or freezes requiring a reboot.
So give it a shot, and let us know if it works for you!
*This solution was taken from Link: Betheda’s website
*Image from: here
Popularity: 48% [?]

tostyle - December 28th, 2008 at 10:19 am
i have this problem but i dont have ffdshow or any other codec packs like k-lite. does any one know of another to fix this.
admin - December 28th, 2008 at 11:31 am
Hey. Make sure you also don’t have CCCP (Combined Community Codec Pack). If you are sure you don’t, it could possibly be a hardware problem. Can you list your system specs? We can try to figure this out.
Rolf - March 6th, 2009 at 7:31 am
I tried it 5 times, dont work for me..
any other ways.? mail me: Rolf_vinther@hotmail.com
StiX - April 23rd, 2009 at 10:41 am
I tried all these solutions and it dont work for me…
I have CTD everytime when im outside in the game world. There’s one good solution, but game starts being sux on Window Mode with 800:600…