Hi Allen,
I've had a test board up and running prior to that as a prelude to doing the migrations (and was very impressed by the facilities available).
I ran the import twice; once using the recommended method of not creating the administrator user prior to the import, the other time creating the administrator user first. Both failed; the only difference was that the second time resulted in the creation of an administrator user who was logged into the control panel (I didn't log out) whilst I was doing the migration from the old board, and thus could still fiddle with the settings.
As for the server, I have full control over it so I don't think it's anything that happened during the import. Nevertheless, I'll try a migration with another board (I have a few to migrate) in case it is data-related.
