I would stop using games for windows live. The game doesnt need it.
If you run the game normally it puts , Saves in (user signed in) My documents\My games\Fallout 3\Saves ...
If you have some save points from Windows live you want to keep. Sign in load up ... Then make a save of that point.
They should appear in that folder now. Run the game from Fallout exe. from now on.
Ive read something about this problem , and you can move those saves to your live I think. I just have no Idea where the folder that live is useing would be , since I dont use it.