I just came back to reply to your old question, but this sounds like your still having the same problem so here's my solution for you:
First nero is the bomb! it is 100% heterosexual. In order to over burn, nero must be in disk-at-once mode, so hit the multisession tab, select no multisession, then hit the burn tab, and select disk-at-once.````````````should work
good ruck