strange radio/defrost problems

When I start the car up cold and turn on the rear window defrost button, some radio stations won't come in. The second I hit the button off, the station comes in perfectly. How the heck are the two related?
If there's one thing I've never been impressed about Pontiac, is there electronics.

If your antenna for your radio is on the rear windshield like mine, they happen to be right next to one another! dunno why its happening though, good luck