Thanks; I had previouly duplicated all folders precisely as structured in the device's memory, but to no avail. You're saying that the original map must be removed, or that it can be left in? Can you detail the folder structure on your SD card in greater depth, because this technique isn't working on mine? Doesn't matter so much anymore, as I was able to update all of New England (all I'll ever need) and maintain maps for all 48 continental states by removing Alaska, PR, and Hawaii, and all voice files that I'll never need. I would, however, like very much to be able to load Canada onto the SD card.
I also accidentally neglected to backup a couple states before loading the updated maps, and I have noticed that these maps are entirely different (not simply POI information is being changed as previously stated), because the unit provides different directions after loading the higher-POI file; is the map information itself as accurate and up-to-date as the original files (I'm thinking that they're older versions, despite the higher POI)? Also, do you know of any location where the original files are posted on the Internet? Thanks.