Hi I have the extra TV's installed as standard with the car and the DVD player broke a while back, I replaced with one off flebay and everything worked fine, now sometimes mainly when I want to watch it as the driver on the nav screen when I pick the other half up from work (I'm usually waiting so it's good to watch something) the tv / nav screen only says mute and I can hear Audio, yet try it a day later and it works fine?!? Please help

Thanks