My car is doing the exact same thing. I disconnected the battery last night to for to reboot the gps and it worked for a short while. From what ive been reading on here the gps unit is crashing and proabably needs to be replaced.

I just repaired the thermostat so im not too thrilled about this new development. I gonna try to just unplug the gps for now, and upgrade to the mk4 unit later. Good luck with yours. If you find a better solution post it. I may want to try your idea.