So far, my 3520 has had no problems. When I first got it, I even tested it with the Enterprise disc that the 2500s didn't like. It had no problem. The 3520 even was able to read some discs that my Lite-On DVD-ROMs and 411@811 had problems reading. Do you have any specific examples of other titles that cause problems on NEC drives (particularly on a 3520)? If so, I'd like to see if I can find one to test...