Could be a Family ID conflict with existing maps in the Mapsource registry, or maybe it lacks some necessary files. To check what kind of errors I suggest to use mapset toolkit: http://sites.google.com/site/cypherman1/ Francisco Moraes wrote: Hi, I've downloaded the North Carolina OSM from Cloudmade and ran through mkgmap (tried all stable versions). I used the map successfully on my Garmin but when I uses the nsis image and installed on MapSource, MapSource fails to start with the following message: App: MapSource At: 4/19/2011 7:46:51 PM (UTC) OS: Windows 7 (64-bit) Service Pack 1 Processor: x86, Processor Level: 6, Processors:2, Model: 23 Stepping: 10, RAM: 4087836 TDB_REGIONDIR.CPP-103-6.16.3.0 Language ID: 1033 Part Number: 006-A0041-00 Build Type: Release Any thoughts on what may cause this? Francisco