When you launch from "Fallout3.exe" it does load correctly?
Crashes are usually related to the mods you have installed, not caused by FOSE. Launching without FOSE should tell you if a mod is responsible, though FOSE won't function, of course.
A missing master file, or a messed up INI file can both cause the game to crash before getting to the main menu.
The game launches correctly from Fallout3.exe, yes.
Actually, I'm in the process of trying to get FWE to work and in the description on Fallout 3 Nexus it said this:
"Ensure that FOMM and FOSE (Fallout Script Extender) are up-to-date and properly installed."
So yeah, I'm basically trying to ensure that FOSE is properly installed. But quite obviously there's something wrong since the game crashes when I'm launching it with FOSE.
Should I maybe try to reinstall the whole thing?