Actually, it's rather simple. Basically, I can't progress more than a few minutes into the game without everything freezing up and CTD-ing. No error message, nothing. Though once I was able to get as far as the GOAT, then it crashed.
First of all, I really hope that you have the original version of the game, because this DOES seem like a common corrupt crack .exe file from a pirate release of the game.
If you do, then.....uhm PM me 
Secondly, if your game is original, the first thing you should do is contact support, to find out that they dont give a rat's ass whether your game works or not.
Also, if your game ISNT a pirate version, then this sounds like a common "OMGWTF-my-OS-is-screwed-up" kind of case. In which case I cant really help you, because it could be anything.
Things you can do that might fix this problem:
1. Make sure you have all up-to-date drivers installed for your Motherboard, Gfx card, Sound Card, and if you have an AMD CPU, the necessary drivers/fixes that AMD releases from time to time.
2. Make sure you have the latest DirectX installed to your Windows. If not, you can easily download it from microsoft.com
3. Make sure you have all the necessary Windows updates required for the game to work. Things like, .NetFramework, MS Visual C++, Service Pack 3, are essential for Windows to run certain programs/games. I'm sure you already know that.
4. Lastly, if all else fails, then run a deep-scan virus search with an Anti-Virus that you can trust. It is a possibility that a virus might be interfering with running programs and kill certain processes.
I have 1 more thing in mind, but I need more info/feedback on your issue, in order to help you further.
P.S. As I understand, Fallout 3 doesnt freeze in a very specific part of the game, right? The crashes are random??
"We were inhuman beings....butchers on a field of corpses....corrupt and depraved....only a sum of viscera, blood, and bone - Creatures without soul."