I have tried to back-up the Nav system disk (Version 3.0 US/CA 03R4) in my 2005 Escalade. I want to avoid having the disk stolen and having to pay an arm and a leg to replace it. As the disk contains over 6 GB of information, I have had to use a double capacity single sided DVD to copy it. However, the system disk seems to be encrypted. Does anyone have an idea on how to decrypt and burn a copy? Thanks in advance.

If it's using CSS encryption (the normal DVD encryption for movies), you can use DVDdecrypter. It's free on the Internet. It's not a for-sale thing, so don't feel like you're stealing it. It's freeware - written by somebody (or a group of programmers) with the intention of giving it away for free.

DVDdecrypter will copy it but also remove the encryption protection from the copy.