2004 cl600. about every 8-10 starts my nav. screen freezes up and i can't use any functions like radio, etc. the mercedes emblem on the screen is not clear and i can't even shut off the system. after about one minute everything starts functioning properly again. today i noticed that when i shut the car down everything shut off, but there was a light in the on- off/volume button. when i pressed the button the radio came on. i tried shutting off the system and i couldn't. the key was out at the time. about a minute later the light went out and the radio finally stopped working. any feedback, or ideas would be greatly appreciated.