For those who are thinking of updating from 5.40 to 5.60, there seems to be quite a serious bug with 5.60 as reported here:
http://garminmontanagpsr.wikispaces.com/Firmware#x-Firmware History-5.60
and
http://garminmontanagpsr.wikispaces.com/share/view/65927798
and if you still want to update, 5.60 is here:
http://www8.garmin.com/support/download_details.jsp?id=5335 or use Garmin Express
http://garminmontanagpsr.wikispaces.com/Firmware#x-Firmware History-5.60
and
http://garminmontanagpsr.wikispaces.com/share/view/65927798
and if you still want to update, 5.60 is here:
http://www8.garmin.com/support/download_details.jsp?id=5335 or use Garmin Express