Problem with Pioneer DVR-107D

Howdy guys, just a small problem with a new DVR-107D drive a friend bought for their home computer. When burning a DVD (ISO), at the very end of the burn, Nero (version 6) says the drive said (you know what i mean!): "Invalid field in command" then nero says it can't finalise the disc, and the burn fails. After this happened a few times, I updated the firmware, checked all the burn settings and everything seems fine. Maybe the media is no good? Well it was all one brand, but they were in individual packaging. Anyone know what this error means? Thanks for any help, guys.

<Edit> In case someone asks, the disks were TDK DVD+R 4x

Did you update nero?
Have you used the nero info tool?