My navigation worked perfectly before but it started acting strange. It could only open "settings" or "shut down" in the menu. When I tried to access other menu options navigation froze, then went into navigation mode after a minute or so and then no navigation button worked. Satellites and everything where online, GPS signal was good, car was being tracked perfectly but no buttons like "enter", "back", "up,down,left,right" worked.
FIX:
1.In the trunk of your car there is a dvd player for your navigation.
2. you will have to disassemble the player, find the lazer lense and clean it.
3. put everything back together.
4. navigation works perfectly (1000$ saved) .