I'm guessing here, but presumably you've downloaded a ".img" file from somewhere like http://garmin.openstreetmap.nl/ . Your Windows computer sees the ".img" extension and thinks that it's a disk image (something that you might burn to CD), but it isn't. Try following instructions such as those at http://www.dcrainmaker.com/2013/05/download-garmin-705800810.html. If you search this site for Garmin you'll get lots of similar questions that you also might find helpful. answered 06 Jul '15, 23:59 SomeoneElse ♦ |
Please tell us exactly where you got the file from ("from OSM" is not sufficient - a web site URL would be good), and what the name of the file is.