I don't know if this has been mentioned before but either exporting Unencoded Quest Files or using the auto-backup feature crashes zquest-w under Windows XP.
The Unencoded Quest File generated does work, as I was able to make some maps in Mapmaker using it, but I don't know if the backup file generated before the crash works. (It would probably help to know how to load a backup file, then perhaps I can test it... )
I will try to gather some documentation regarding the crash... when I do, I will post it.