I got a pack of ridata dl dvd-r free from newegg, the first one I tried to burn, my burner also a Nec 3550a would not even take my disc. I found some firmware on Liggy and Dee's site that made it possible to burn and play, not only on my new Sony, but also on my old Toshiba stand alone, that is very fussy about what it takes. It can only read dvd-r. If you look up to an earlier thread about firmware and Nec3550a by Liggy and Dee, you might find the answer to your problem,I did. Nec also has an updated firmware, you might want to check that out too.