What he said. The universal wiring kit for our cars, isn't. You need to connect the ground to the chassis. I always had luck using a ring terminal and attaching it to the stock radio bracket. Using the antenae for the ground is bad, especially on the newer decks with more power.
BadAhab said:"Our cars are a bit strange in the way that the antenna must carry power"
Thats because your ground is going all the way through the shield on your your ant lead to the body of the car. Just take a short piece of wire or use the ground lead on the stereo and put it right the the body of the car. Thats bad to have your ant as ground.... badddd.