I'll ask folks here if there's a suggestion. Hang tight.
It seems to be related to the fallout.ini and the fallout_default.ini files. If they are changed, say for mods, then it'll need to check them through steam, delete and reinstall them in order for it to work.
Thats kinda balls, since it kills the mod in the process. Since steam does all this updating automatically (and without my damn concent)you've pretty much shut down my ability to play the game until a work around comes out for it. Editing the new .ini files in order to allow for the mods breaks the game once more. And no, I won't play the game without the mods, defeats the purpose of playing since I don't enjoy the core rules/avatars/whatever/take your pick.