Hi Howard, I had exactly the same situation when swapping DVD's in my GS.
The only way to prevent the constant DVD reboots was to disconnect the small 12v battery, have a brew, reconnect the battery and then the DVD started up okay.
It's been okay since too.
Disconnecting the small 12v battery will loose your trip readings/etc but nothing major occurred for me.
The battery disconnect was detailed in the brief instructions I received, did you receive any guidance with your DVD?
Let us know how you get on.