In-dash dvd player makes whissling noi...

A few months ago I put a news stereo into my car, one of those in-dash DVD players with GPS. It worked mostly fine for a few months, and just yesterday when I turned the car off it started making a really high pitched noise. Similar to a noise you can hear from a power inverter when the car gets turned off. I turned the car back on, the noise stopped. Turned it off again, and the noise started again. So I had to leave. Then when I came back, the noise would not stop even after I turned the car on and the stereo won't come on now. so I unplugged the stereo, changed the fuse, that didn't help, then isolated that the noise comes when the stereo is connected to the ground wire. If I disconnect that wire from ground, it stops making the noise, but nothing works regardless. Ideas?

Also, for the first 3 month, the other problem I had was with the FM radio. The music sounded great from a CD, MP3s or DVDs, but the regular radio sounded horrible, very distorted.