Man of Honour
why it doesn't crash in the Vault is odd.....this is common to nearly everyone, because you're inside the vault for quite some time....the open areas outside are more graphically intensive and it crashes far more in the Wastelands than it does down below in the subways or inside buildings.....very strange. ...... Crysis was very similar too, but didn't crash nearly as often....that used to crash most of all at auto save points.
i'll try everything mentioned
Inside the vault the CPU has little to do, whereas outside it has to start calculating the positions of all the nearby monsters, NPCs etc. There's also obviously a lot more graphics to be processed. I would guess that the same thing is happening here as happened with Oblivion: the game is just finding the weaknesses in your rig. I run a fairly seriously overclocked i920 and Fallout3 has never crashed on me. I've had a couple of lockups, but I know they are the graphics card overheating. And I'm running an Xfi as well, so I'm not convinced about that theory.
But what has been said about corrupted saves is true - except generally if the saves are corrupted the game will crash the moment the save loads.
M