Oh dear, it's Garmin. I've got an Edge 705 - fantastic hardware, ABYSMAL software. This is just one example of how Garmin makes everything as difficult as possible for the user. When you buy the unit, it says 'Mac compatible' on the box - but what they don't tell you is that you need a PC as well as your Mac to get the maps onto your GPS.
The best solution I've found so far (after 4 months using the unit and loving it) is never to touch any of their software and use a third party app (I like Ascent) as much as possible.