I have been using DVD-Rs for backing up my daughters movies and have had problems with several movies. They play fine for a while then start getting blocky and eventually lock up. I can eject the disk and it will play just fine through the area that was causing problems before, but will start messing up withing 10-20 minutes. I have tried several brands of media with the same results. Most movies work fine but enough of them mess up to where it is anoying. They all work when playing from my burner, but mess up when playing in a set top player of a DVD ROM drive. I'm just wondering if DVD+R disks are more reliable then the -Rs. I have a Pioneer DVD burner. I think it is a DVD-105.