I repair these a lot, I always have a few at home. As a matter of fact, by now 80% of the pre-2006 navigation units need repair.
The main problem is the BGA chips start to develop a cold solders underneath them (figuratively said, BGA have no pins). Pretty much the same problem as the Playstation 3, Xbox, etc. If you try to update/reprogram yours and it has loose connections the update may not go thru and the unit will be completely dead. But if it is a HW problem this is imminent. I can send you a special recovery disks for the CCC if you want to try and can help you with instructions if you want to try to repair your unit.