Hi all, I had the same problem, so I phoned Navman direct and they gave me the following advice, basically you need to format your satnav. It works !
Hi the resolution is :
Connect device to PC > Start > My computer.
Right click on Navman under removable drive left click on format. (must be FAT)
When done open Navdesk
Disconnect device let it restart then re connect the device.
When Navdesk synchronised click Tools > reinstall software.
When reinstalled the software and you have had the screen “software successfully installed” click okay
Disconnect device, let it restart then reconnect
Let Navdesk synchronised and more tabs will appear.
Tools > Recover keys with the DVD into the drive
When downloaded disconnect the device let it restart then reconnect.
Now you can install the maps and voices as standard.
Gary Tetlow, October 2009