I was kind of having the same problem a while back.
If you do a search for my threads, you'll see what I mean.
Anyway, I too kept trying to burn onto a blank DVD.
The problem I was having was that I kept getting an error message telling
me I was using the wrong media and that I needed a blank CDR.
It turned out that the problem was with my OS.
I had to reinstall XP and the problem went away.