Sounds like the same video card problem many had on release.
See Fallout 3 has certain graphical packages for certain levels of hardware (not the same as the settings) Some graphics cards were assigned a package, but they didn't actually put the package into the game. If you changed the (I think it's an INI file) file to another package, you can load the menu, but cannot play because your video card cannot understand how the game is telling it to render. >> So you might need new hardware.
...If that's not it, then I'd like to know what you did to load the menu at least XD