GPS Problem

I have a 2001 740LI that has been a great car. At 100,000 miles I had three problems. 1) the moonroof jammed and will not opem (glad it is closed). 2) the dash pixels began to go ( contacted BMW NA and they agreed to give me a new unit if I pay the labor, and 3) my GPS went out. I have the unit with the female voice and it will track my current location, but will not navigate. On the right top of the screen the GPS letter usually appear in green with spots when the sats are found. Now only 1/3 of the GPS turns green. 2/3rds is black. Does anyone have a suggestion as to what may be wrong. My dealer said it was my disks (not) or simply wanted to replace the entire unit.