I think we're talking at cross purposes here.
Randall's ASUS drive works, my LG drive doesn't. Thanks for the suggestion of the ASUS Randall.
Changing the burn speed doesn't make any difference, because it never starts burning; ie it errors out before commencing.
I'm using TDK or Maxell DVD-Rs, single layer. Media is probably not the issue, as it never commences burning under Max OS, and burns perfectly well under Windows 7 with the same machine in Bootcamp.
An image of the System Profiler report for the drive is below:
and the Disk Utility report for the drive:
Simon