07 Navagation problems

[protrax]

Hi all when I first bought my 07 Denali the navigation worked good it had the original disk in it but everything worked fine . After a while it did not work anymore and the screen would say the disk installed is not a DVD map so I would take it out and re load it back in and nothing so I eventually bought the New 2011 disk from Gm Then the Navagation started working again and was nice with the updated streets . Problem now is after 3-4 months it no longer works again and the screen says the the disk installed is not a DVD map.

I have tried putting it in over and over again and nothing , I have even tried the original disk to the truck with the very same results . Is it Dirty ? What can I do to get it to read the disk ?

I tried to put a cd dvd cleaner disk in and that did nothing

Thank You for your time !

[protrax]

This is what the screen says