Fallout 3 GoTY crashes on startup. Nothing but black screen shows up before it crashes. I bought it on Steam.
I was able to play the game from disk and not GoTY, without any DLCs about a year ago on the same system - Windows 7 x64. I bought the game recently because I lost my disk. I've reinstalled Windows in the meantime once.
I've got DirectX installed when launching games on Steam, also installed using a webinstall from MS website recently, so it's up-to-date. There is no other game that crashes too. My Nvidia drivers are latest version also.
I've tried reinstalling the game but it still didn't work. I've tried deleting F3 folder from My Documents which also didn't help.
I've tried compatibility modes and "Run as Administrator" function, neither did help.
I haven't changed anything in my hardware so it's not hardware-related.

What might be the problem?

Did you try deleting the Fallout.ini file located in My Documents>My Games>Fallout 3?

It would be nice if you would read my post before posting a common solution.

I'm in the same situation (except my recent Windows 7 reinstallation was from a disk). Apparently another user has found a shell extension download that solves the Windows 7 incompatibility issues (though it may not work with mods). I personally don't know anything about it yet, I'm afraid, so I can't point you in a more precise direction than a Google search. I'll report back here and in a few other threads here if I find something that works well--mods or not, I'd like to be able to at least play the game I paid for.