At first I blamed myself for burning at high speed then I dropped all the way down to 4xSpeed and I still get coasters with my Pioneer DVR-108 & Ritek DVD media.
I have now updated the Firmware to v1.20 so I hope this will now solve the problem.
Please let me now if what I have experienced to be a common problem with old Firmware on DVR-108 so I may rest assured.
Thanks