Nope, I've duplicated this behavior with Nero 126.96.36.199, Alcohol 120%, Nero CD/DVD speed create data disc, and firmware version 2.f6 through 2.fc
In the USB enclosure Mad Dog provides DVD-R discs will not burn. +R discs are fine and burn all day long in this drive but for some reason, I can duplicate it time and again. Sony, Memorex, Fuji, Imation. Now here is the kicker, if I take the drive out of the housing, and attach it to an IDE cable, it burns -R like a champ. ISO, image vob files, Data discs, whatever. The drive and the USB housing and the software are communicating poorly with -R is my best guess. When I pulled the housing apart it has an ALi chipset, any body else experienced this with an NEC 3500A in a USB 2.0 housing with an ALi chipset?