Get Nero CD-DVD Speed test V3.61 from http://www.cdspeed2000.com/
You point it to the DVD drive, and use the START button, Default it will chart the speed and RPM, and later run through some other numbers I mentioned.
1)Use both pressed and burned disc to see how it runs. There are many images posted to the forums.
2) There is option on menu Run Test.Create test disc. This will write a test disc, so you have to waste one for good cause. It will show you how your drive burns under optimal conditons. Do NOT use the system for anything while burning and testing, and close all programs that you can.
Also, maybe it is the NEro installation that is not worjking smoothly with your setup. The CD-DVD test will tell you, or untill you solve the probl;em, create ISO image and try writing it with free program DVD Decrypter.