I see from your scan that you are using RITEKG04. What does that disc scan like in the Nero CD-DVD Speed quality test and also what is the transfer rate test result like?
This is one of the reason that it's good to own a DVD+RW disc. If you don't know whether you have a media, software or hardware problem you can burn the +RW to test and eliminate what is causing the problem.
Also I wonder why your sample count in that scan is so low. I see it's not a full disc but that is still a very low count for a burn of that size. What system do you have and how busy was it during that scan?