2004 LX470 - My new LX470 is having navigation systems issues already. When I first got the LX, the bluetooth would sometimes remain muted after a call and the only way to get the radio going again was to restart the truck. Lexus replaced the bluetooth amplifier and this seemed to solve the problem. Now, the issue I am having is much more serious. The navigation screen will display an ominous "check the system" message and all of the buttons / systems surrounding the navigation screen fail to function. Sometimes the screen will go completely blank. Other times, an "audio system off" message will be displayed even though the radio is on. I have also received messages (not exact) like "the external device is not connected" or "the air conditioning system is not connected." Sometimes, out of nowhere, the radio will turn itself off, the antenna will retract, and then the systems seem to return to normal. Lexus has ordered a new navigation screen and plans to install it today, but it seems to be a logic problem, not a video problem. Has anyone seen this issue? I don't like the idea of having tempormental demons in my $65K car... Any help would be much appreciated.