I must admit I don't know what can be wrong but you may try few things (to filter plausible causes out).
I am sorry for just guessing but:
1. backup your working version - just to have the point of return
2. try new version without config.ini - some option is bad,
3. try to overwrite old EXE with new one (only EXE) - linked DLL issue,
4. try to run BBCeditor from fully accessible path (not Program Files) or run it as admin,
5. check your anti-virus policy - maybe you've added old version there,
6. try to reinstall framework - last resort.