I have an issue with a NEC ND-4550a DVD+-RW drive.  It will burn CDs, but not burn DVDs, although it used to.  I have put the drive into two different PCs, with the same effect.
The Nero Info tool tells me the drive is a +-RW, but in Windows Explorer it just shows as a a CD drive.

The drives firmware is version 1.09 and the OSs on both PCs are XP, although one is XP Professional and one is XP home.

I haev seen several references in forums to the problem, so I am not alone in having this problem, but there does not seem to be a definitive answer and solution. Does anybody here have one?