I would hate for you to kill another disc, but can you burn to disc properly at all using the built-in Windows DVD writer? To this day, I still use 3rd party software. I was prompted to buy Nero Burning ROM and use UltraISO to get around using Windows to burn stuff because of the coasters it has a tendency to make. The rate of failure seems to be above average. Success seems to be based on what kind of burner you have. Check and see if you can burn something to a DVD-R using Windows to begin with. If that fails, you know that either 1) Windows built-in burning software is not compatible with your DVD writer or your discs. OR 2) The DVD-R is damaged or broken.
I have not used or even tested Windows Backup on DVD-R for a few reasons: It appears making an image backup would not be possible. If you are like me and are using 200GB of disk space, you would need to use 43 DVD-R discs (avg. capacity is 4.71GB) as a conservative estimate. I do not know if Windows Backup supports dual layer, but thats still 24 DVD-R dual layer discs to backup 200GB. A backup HD seems like a better option.
Because I do not have the details for you, I can't be of assistance in this matter. I can only suggest from experience that it may indeed be the Windows support for your DVD burner or the media itself. I believe the number of people doing DVD backups with Windows Backup is probably a significant minority to the point that it could be an unidentified bug. I have abandoned using Windows Backup in favor of offline bare metal backup software that I now run around once a month (full backup). For important docs that don't take up a lot of space, I use Dropbox for both backup and file sharing.
I know this is not the answer you are looking for, but I am willing to tell you my experiences with what I consider to still be poor areas in Windows (Disc burning support and backups). In these two areas, it seems like using 3rd party software is an absolute must if you want to get serious in either category. I think users who don't have many files and applications can squeeze by with Windows Backup, but not by much. The biggest problem is when you lose the whole OS and find out the shadow copy didn't work right.
