Nec 3550-a is the burner. Used to play all dvd's but now it only recognizes some. homemade dvd data disc are recognized as raw data in explorer and can only be read with isobuster or the like. I have reinstalled device to no avail. I have deleted upperfilter and lower filter values. gotten rid of all software ie: roxio,nero,daemon tools,alcohol. Why does it read some and not others. any help is greatly appreciated.