I use those to, but I havent encoutered movies that I cant burn. You have to watch out for Sony Arcoss DVDs....ANy new DVD produced by SONY may have Arcoss protection...
Not sure if they were Sony's or not.
The error I got was shrink saying "out of memory". I ran a few searches, seemed to be a common problem on the movies I was burning, so thats what led me to using clonedvd.