Have you tried updating to the newest version of Nero?
You could try the free RecordNow software that should have came bundled with your drive. Sometimes it's 'hidden' on the Sonic CD (ie it doesn't show on the initial splash screen that comes up when you pop in the CD). Try installing it. See the RecordNow guide in my sig for how to burn data DVD files with it.
It is always a good idea to try the drive in another computer to verify it's not a hardware problem.