OK, I picked up my NightHawk Black Beauty w/Nav this past Saturday. I have been reading posts here for three months and checked for all the major problems, i.e., (the thud, the mirrors, etc). I think I have a new one! When I turn off the radio and shut down the nav, I have a very high pitched ringing. I noticed it on a very quiet day and it has since been driving me crazy. Its kinda like the sound a TV makes when you first turn it on or put it on mute. I guess I could just keep the radio on low to mask it, but sometimes I enjoy the solitude that a car can give you. Or maybe the interior is just so quiet my ears are ringing! Na couldnt be! What do you think? Anyone else have this prob!