[stumbo]

In have a similar age car. But being in the UK there may be other Nav diffrences. I diagnosed this same problem on mine from symtoms:

Intermittent (month/week on month/week off) failure of the Nav unit to pick up Satelltes. Dicking about with the connectors at the back of the Nav unit and ejecting the CD did get it to lapse into an 'on' peroid.

I'm convinced its connector related and that the actual units are fine.

To do it properly, I need to get all the electronic kit out from there and trace the cabeling since its very hard to do anything in situ.

 

[mottati]

the 00 cars with the mk2 system (small screen nav) also had a separate gps receiver (integrated in later cars) so perhaps that has gone bad. You could probably pick up parts cheap off ebay or perhaps here in the classifieds, from someone who upgraded their nav (or upgrade yours!)
Mike