I have used dvd shrink to make back up copies of some of my kids movies. sometimes no problem and it works great. Other times, it goes throught the process and won't burn. I wasted a lot of dvd's so I got a re-writable. Figured if it worked, I would then put in on a write once. It worked on the re-writeable but then would not burn to the other. Any ideas why some movies won't burn? (size is fine).