I just had my audio system shut off, and couldn't turn it back on. Also, Navigation then would show up and you could set a destination, but then not function. Looked all over, then came across a posting about this issue in the 09 Navigator with a THX radio system. There is a software fix mentioned TSB 09-5-9 , but in the meantime it said to reset the audio to disconnect the battery, then touch the two leads together to drain the system for 5sec. Then reconnect, positive first, neg last. Sure enough, that fixed it. Everyone kept saying it was a fuse, but that was fine. Posting it here for the next guy, if that is his problem too.