In response to the other posting about the radar detector, I DO have a radar detector, but it is stuck up on the windshield next to the mirror. I do know the gps antenna on the new IS is located in the back window, not the front. I also know the radar is not the culprit since I picked up the car once from the dealer after they messed with it again, and it started !Removed! up again before I left the parking lot and the radar detector was still in my bag and unplugged.
As for my current status with fixing the issue, I have been to the dealer on 6 separate occasions. They have replaced the disc...that didnt work. They replaced the whole nav unit the last time I was in....that didnt work (but it did make me lose all my saved places, dang it). I drove to San Francisco this last weekend and spent about 1/2 the trip there randomly traveling off onto side roads off the freeway according to the nav, even though I never left the freeway. And when I say travel, I mean suddenly take a 90 degree turn off an off ramp and head off for 5-10 miles or so and then jump back onto the freeway. It makes the directions fun to follow. "Make a legal U-turn in 1/2 mile." How can I make a U-turn on the freeway?!?!?!?? Another new issue since they replaced the nav unit is nearly every time I start up the car, the nav resorts to the east coast, which is an issue since I live in Cali.
Also, I have been plagued with other problems caused by the repair people at the dealership that has been working on my car. For example, my rear view mirror has fallen off, and I have mentioned to the service guy on 3 occasions when bringing my car in that it needs to be fixed since the plastic housing that hides the wires is missing and everytime I pick up my car it is not fixed. I could legally lemon the car just on that at this point.