Huh, I just noticed I do not have the bg2 fixpack installed... (mutters curses under his breath). Let me try again and reinstall and if the problem persists I will be back.
Edit:
- Ok, reinstalled and done the NI corrupt file check right after installing ToBEx (after starting a new game with ToBEx just to make sure everything is fine -- it is). Same errors. So this has nothing to do with BGT or what not. Maybe my GOG installer is corrupted?
- Installing the bg2 fixpack has solved some of the problems. Only (lots of) wed files missing bif's remain. That is better than nothing I suppose.