Has anyone experienced an intermittent rubbing noise coming from rear of car? It can only be heard between 15-20MPH. It is a SHH, SHH, SHH, sound. I have taken it to the dealership 3 times. The first time they deglazed the rotors, the second time they resurfaced the rotors, and the third time they said it was normal. B.S! I called the Pontiac hotline, which investigated, and the dealership told them that the last time I took the car in, they could not hear the noise. Once again, B.S! They suggested I take the car to a different dealership.....WOW... what a great way to resolve a problem and to satisfy a loyal GM (5 new GM cars in the last 10 years) customer. HELP!!!! My car is a 2005 w/a.t.