I just did 04 nav install on my 05 cts, It worked perfect 4 about a week!! WELL atleast until last night. It started up, the crest came on like normal, put in reverse and backed out. Then BLAMO!! Blank screen!! Radio still plays but unable to switch source from steering wheel.:banghead: I was messing around and found the diagnostic screen about an hour before, but I didnt think I actually did anything. (I was trying to play a burned dvd) I even pulled it out and checked all connections. None of the buttons work on the nav but I can insert and eject cd's, Dvd wont accept any. I bought from EBAY and it was straight plug and play. NO WARRANTY!!! :annoyed: Any idea's??? :hmm: :hmm: :hmm: Can I even take to dealer and have them diagnotic it??