Welcome to the forum. Had same problem with Ritek and 3550 when I first started burning D/L disc. 1/4 of the discs were coasters, and the successful ones had plenty of errors around the layer break. Like chef said, the problem is with the media which is Ritek. Ritek is just the worst in DVD right now including S/L and D/L media. I'm about done transferring all my burned D/L discs to Verbatim MKM001. Verbatim is the best in D/L so when they go on sale, which is often these days, stock up on it.