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.