I've had problems like this....
Perhaps this might help.
I've found that the capitalization of the file is sometimes a problem. Ndisles either has to be in all caps or none at all - I don't remember which.
For offline use, you can change your map by modifying (or creating if it does not exist) the file curterr.cfg in the settings directory.
It's a text file, just add the line "ndisles". (with out the quotes)
Nexus