If your DVD burner supports using Nero CD-DVD Speed, then d/l the latest version (if you don’t have it) and see if you can run a transfer rate test on the disc in question and make sure to also have it run a burst rate test; if it’s a CD, then you should get a burst rate of ~ 20-21 mb/s and if a DVD of at least 22-24 mb/s. If your burst rate holds up, then that’s a way to know your burner is good; if it’s far below either of those #s, your drive could be failing. The reason why I suggest the Transfer Rate Test is that if you test the disc and it produces a smooth curve, then it’s not the disc; if you get one or more major dips in the curve and/or get a partial read then “no additional sense information” message, then it’s the disc that’s the problem. Another way to eliminate it being the disc is to at least take it to one other computer (a friend’s) and see if that computer’s CD/DVD unit reads it just fine and try that a few times to make sure. If you eliminate the disc that way, then again it could be your CD/DVD unit is indeed going out (if the burst rate test can’t be run/you can’t use Nero b/c of your unit).