Hi Divemaster,
You do not say but I am suspecting an older model S.
Some techniques are to delete as many "old" destinations no longer used from navigation system.
Reset any and all trip computers no longer used.
Remove any websites from the browser - leave it blank or set to tesla.com
Do not leave it set on Google or another search engine. (Even empty or blank)
Reboot the car.
Try to see what the GPS indicates outside on a road not in the garage.
It might help - Give it a try.
Shawn