I recently purchased the "Sony DRX840U 20x External Dual-Layer DVD Burner" solely to burn ISO images etc. The process was easy enough, after extracting the VIDEO_TS folder from the .rar I opened it into Nero and attempted to burn a DVD. Prior to attempting to burn it I had to go through DVD Shrink to reduce the size from around 7.5 gigs to a little over 4.5 gigs (to fit on my DVD-R which hold 4.7). However, the problem arises after Nero asks for a blank DVD to burn to. I put one in and I hear the burner starting up and getting ready to go, nothing happens after that. The prompt still says to put in a blank DVD. I had no problem burning a CD on it, it recognized the CD-R fine and ripped it. I'm new to this, by the way, so thanks in advance to anyone who can be of assistance/guidance.
Unplug any other USB device and try it. Plug it into another PC and try it. See if it has the latest firmware. http://sony.storagesupport.com/product/258#drivers