I have a 2007 Tahoe. All of a suddent the navigation isn't working, the marker showing where the car is located spins around in circles and the location is wrong. For example, if I'm driving south on I-75, the little triangle will shoot north, then west, and the location will be about 5 miles away from where I acutally am. Anybody have any ideas as to what the problem may be?

 

Could be the nav itself, a bad disc, pinched\chaffed VSS Wire, or the GPS antenna is malfunctioning