Just got a 3520a, never used it yet to burn a dvd. I also just bought a spindle of 50 sony DVD-Rs and every time I put in a blank dvd it freezes my computer and does not recognize the drive. As soon as I remove the dvd everything is fine. I updated to firmware 3.05 and still same problem.
CD-Rs read and write without a problem. I put in a DVD movie at it also played without a problem as well.