But TBH the problem sounds more basic - are you connecting the GPS as an external storage device (not good), or is it being seen and model type correctly identified by your Garmin software (in 'Send to Device')??
No it thinks it's a F drive
It also "can't unlock the map" after it's downloaded
Martin we are talking about a Vista, right? And you're using Trip & Waypoint Manager or Mapsource (ie Garmin's software as supplied with the unit) to load the Route but some other method to load a 3rd-party map, is that right?
If I've made the right assumptions there, T&W Man (or Mapsource, or Memory Map, or EasyGPS, or GPSBabel) can
NOT transfer Routes etc while the GPS appears as a ext drive.
To transfer Routes etc, just switch the unit off, switch it on again and connect via USB, and use any one of the above software (but I would suggest
T&W Man ideally Mapsource). By default it should connect in non-ext drive mode - your File Manager won't see it. That is good. Your transfer software will see it and may identify the model - eg VistaHCx. That is better.
Transferring the map - if you are creating a map file and then just copying it across to F:/garmin/ - well for a start do that as a separate operation. Switch the gPS off and on again to remake the connection, then force it into ext drive mode.
If you are using Garmin software to transfer the map (or, AFAIK Sendmap not sure about that) then you don't have to even think about where it is going, what it is called etc - just connect in the default non-ext drive mode as above and let the software do its stuff (its quite slow BTW - only USB 1).
Don't know anything about map unlocking but if you're trying to load City maps then that sounds likely cause of problem too.