Just in case anyone else had a mild annoyance by the "Cannot Authenticate Maps" on their BMW Navigator IV for the past several months, Garmin tech support responded with a one line message: Delete the gmapsupp file from the unit. Please let me know if you have any other questions. Works! The error is now gone and there is only the most recent map set (2012.20) on the unit. The unit always was functional before, but as stated above, would always have the annoying message before moving on to the main screen. Jason
ok, so I have three different GMAPSUPP files. IMG, GMA and UNL extensions. I take it I don't delete the IMG file, but which of the others do I delete?