Shrill Noise coming from speakers

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

The radio needed to be rebooted? Very odd.

Since that day when the stereo freaked out or it freaked me out, it's been working fine. Do you think it rebooted itself when I turned it off, and then actually turned off the ignition? Is it just a freak occurance, or do I need to contemplate trying to get help from the dealer? The problem will be trying to instantly take it there when the piercing noise is happening.... otherwise, they will assume I'm another "crazy" client! Of course that noise could send you there but quick! lj