Actually I have done a little checking. The drive can burn at 2.4X or 4X.
(apparently +R burners have 2.4X as the lowest setting)
I would like to try burning at 2.4X (the lowest for my drive) to determine if it is the burning process or the disc which is causing the incompatibility. I am currently trialing TDKs \"1-4X\" (which are only being recognised as a 4X by Nero).
I have used DVDInfoPro and DVDIdentifier and both of these give different answers as to the disk speed for a certain disc. DVDInfo says the disc is 4X only, but the other one states either 2.4X or 4X for the same disc!

?