Audio Systems: Car Stereo Factory, factory radios, gmc envoy

Question
I have a 2004 GMC Envoy.  I am getting CD Error displayed on the screen.  I don't believe there are any more CD's in the player.  I have tried to play a CD and it doesn't play and then the CD won't eject for days.  I just hit the eject button every time I get in the car and finally the CD comes out of the player.  This is also the on board navigation system display.  I am afraid to use the CD for on board navigation for fear that it might not come out.  AS I said...even though I don't think there is still a CD in the player...it will come up with CD error once in a while.  Help if you can.  Thanks.

Answer
there are small metal or plastic plates inside the radio to help you keep all 6 discs apart  if any ot this got damage with a bad cd,cd with a paper label or any other object  no cd is going to play until that is replace
this is a very complicated radio  don't open it
find a good service center for factory radios
sorry i can not help you more