Originally Posted by BigOgre
Came across a very similar issue just this morning and figured if I searched enough I'd find an answer. But seeing as you all brought it up . . .
CN loaded into internal memory. 100k Topo loaded onto SD card. Route developed in BC and sent over - all works fine but only if SD card is left out. Once I drop the card in, Montana tells me route doesn't match map. Check of map settings only shows Topo installed and enabled (along with factory loaded maps) and CN seems to have disappeared. Shut down, remove card, and CN shows back up as enabled. I'm doing something wrong, right?
Sounds like your City Nav and Topo have similar FID numbers....
Did you use MapSource to send them, or BaseCamp?