Hi

Game is Fallout 3 Game of the Year Windows Live edition, game is updated to the latest pacth

O/S is windows vista 64 home premium

I am on the final main quest of the game "Take it back!" and the game is stuck. This is what happens:

I enter the citadel then lab to go to elder Lyons, game goes through dialogue and finishes, but then it just sits there, all the NPCs are just standing, not going anywhere, they make their regular arm motions etc. this is not a game game crash but they are just stuck not going forward as should, not giving me any further dialgue options, nothing. So far I have tried the following to see if this would get fixed but without any success:

1. tried to reload from a further save, many many times
2. tried restarting game with all the optional files disabled, many times
3. tried rebooting computer, many times
4. did checkdisk, defrag, ran a scanner etc.

nothing i do seems to work. i see peoples posts about a similar bug with robot getting stuck like this further up in the same quest, but i dont see any solutions posted for it.

so how do i fix this ?

thanks