What are you trying to burn the mapping cd or the OS for your nav?
It shouldn't be asking for a DVD unless you are trying to make a dvd copy.. if you just trying to burn the OS of the nav then try using nero if ya don't have try getting a temporary one from www.nero.com or try getting the hack version..

make sure if you making a copy of the OS for the nav that you are choiceing the burn of image from the menu...