Ok, this would be a first for me. When i created a world, everything went perfectly normal. But then when i munged it, and tryed to start SWBF2, the game got as far as the loading screen and then it crashed. When i tryed to open it in Mod Tools, the same thing happened, only this time i was able to tell what was wrong. Here's what was in the BFront2 doc:

Message Severity: 3
.\Source\LuaScript.cpp(435)
Script file addme not found

What does this mean, and is there a way to fix it?

It sounds like you deleted addme.script; make sure you have it in the correct folder. (Sorry, I don't know which one it is...)