So what do you have in your Nuvi's Map folder, apart from those cx's, India map and any other maps that you have added? Is your preloaded North America/US map or only your basemap in there? Because i think your NA/US map may be the source of all those little .chk files. If you have no basemap in the .system folder, the only other place it could be on the nuvi itself is in the Map folder.