Help with rear video screen

[aqwk68]

I recently bought a 02 tahoe with an 18" fold down screen in the rear. When I bought it the factory radio we back in it so I bought a DVD stereo for it so I could hook up the rear monitor. Well plugged int the wires that were already ran to the dash and everything seemed to work. Then the first time we went on a drive and the kids were watching a movie the screen just went blank after about 15 min. The sound was still playing just no picture. They hit the power button on the screen but that didn't help. Now the screen is wired to a switch on the dash that also controls power to the screen. So I turned the switch off and right back on and the screen came back on. This basically continues the rest of the time the movie plays only that after the first time it is completely random as to whenthe screen will shut off, but everytime it does all I have to do is flip the power switch for it on the dash and it comes right back on. I haven't had the time yet to stat removing the interior pieces to chase down the wiring and thought I'd check here to see if anyone may have any suggestions as to what is causing this.