I have a 91 DA. it has 250,xxx miles, and performs pretty well for its age. the thing is, whenever i rev high or i get around 50mph mark, my stereo shuts off completly, and a loud beep rings about 3 times from somewhere inside the car (other than the speakers), and then stops. once i slow down, the music comes back on. it doesnt matter if im in 2nd gear, or in 5th, when it hits a certain speed/rpm it always happens. ive searched for days and cant figure whats wrong...