Hmmm...the only thing I can think of is that you might not be switching in Nero...from recording on CD to recording on DVD. You know, that place at the beginning before you determine what type of disk (music, data, etc.) you are trying to make.
Then again, it could be something that's corrupt in Nero 7, so I suggest the old uninstall/reinstall routine...after running chkdsk on the C: partition (follow the instructions below).
How To Run CHKDSK In XP - http://support.microsoft.com/default.aspx?...b;en-us;Q315265
You will get the message stating that chkdsk will be run on the next boot, etc. Acknowledge, reboot, and let it run.