I’ve never tried things like this, but guessing from the error: do you still have an OSM World Routable map installed in MapSource before downloading the map from the NuvI? If so, what happens if you remove that map first?
I uninstalled all 4 maps by an uninstaller program and then clean registry by a registry cleaner. Afterward “OSM World Map” disappeared from Mapsource drop-down menu, but this error again appears when i want to import joined map from Nuvi 715.
How this can be solved?