I'm no expert but it sounds like a DVD 9. Most new titles are
I have the same burner as yours and when I can't fit the backup onto one disc I use DVD2one. Its a three step process and a little time consuming but worthwhile. There are no conflicts with the 105.
The quality of the backed up movie is excellent (so far)
For more help try here
http://www.dvdrhelp.com/forum/userguides/141024.php