Unable to switch to audio display...

I have an intermittent problem with the Nav display on my 2005 in which the nav works, but I'm unable to switch to the audio screen. The only way to fix it is to shut off the vehicle and restart (reboot...). My local dealer has no idea what's wrong; has anyone else experienced this problem??

they should be able to figure it out. Its probably either the navi unit or the display itself. Sounds like they are giving up without even trying.