I have a strange problem with my DVR108.
It burns DVD well as long as I don't exceed the rated media speed, but I have problems when I burn CDs at anything more than 16x. No burn errors are reported, but music CDs won't play after 2 or 3 tracks, and data cd's are hit and miss. Looking at the write side, there are clearly two different regions. The inner third of the disc is darker, as if it's been burnt twice.
Firmware is 1.20, software is Nero 184.108.40.206 (but it's the same with any software), and it happens on any media type, even rated to 52x.
I can live with 16x CDs, but I'd rather not have to.