I have a 2005 s430 every now and then the sound just shuts off when i start my car and I get no radio, CD, navigation, or satellite sound. Sometimes the system will also shut itself off and then on again for a quick second. But my problem is that i'm not getting sound again today. Usually what I do when this happens is turn off my system when i park my car and when I get to where I need to go leave the system off and start car again and it works. What can be causing this?