This is completely odd but with my Rand McNally GPS mouse on, I lose FM reception. I still get reception and it isnt horrible but its much worse than if the GPS is off. And its NOT RF interference from the computer; I really mean when just the GPS is off and the computer is on is when I have FM signal loss.
My cars FM antenna is the on glass array type

Im switching from the current Rand McNally reciever to a Garmin 15L with a Hercules antenna but I dont know if thats going to make any difference with my FM reception issue

Could the GPS signal actually screw up FM reception? RF interference from the power to the reciever? ???