tjipp,
could be alot of reasons I guess. Some checks you can do
1: not latest ioa.exe. yes 0.7.0 is latest "official" release but it exist newer ones.
http://warc.mine.nu/download/ioa.exe always have the latest one. Could be changes needed in conf and so on but it is the latest.
2. Check debuglog for clues
3. What command is it that crashes?
4. Changing in userfiles is a nono if not knowing whats happening
5. If still crashing. let me know how to reproduce it
/WarC