There is a similar question on a German forum (Naviboard):
After updating more then one map with GarminExpress all the maps were locked.Code:Please Login or Register to see the links
GE put the unlockfiles (gma, unl) in the directory: C:\Users\Benutzer\AppData\Local\Microsoft\Windows\ INetCache\Virtualized\C\Users\Benutzer\AppData\Roa ming\Garmin\Maps
instead of C:\Users\Benutzer\AppData\Roaming\Garmin\Maps
Maybe it is also your solution.
Bookmarks