This morning I drove about 4 miles to the bank, the RF stereo was fine, shut the truck off went inside, came back turned on the engine. This shrill piercing noise was blasting out of every speaker! I turned the cd to radio, same thing, I gave up and shut the stereo off. I got to the post office, about another mile or two, when I came back out to the X, I tried the stereo again and everything seemed to be working normally! Anyone encountered this before? I searched the forums and found no mention of this phenomenon.Thanks, lj