Doing a quick google search netted these:
http://www.google.com/search?q=nero+...en-US:official
1. Make sure the firmware (drivers) for your DVD drive is updated. I didn't see you note what drive you're using but just go to the manufacturer's website and they should have it there.
2. Make sure Nero is all up to date.
3. Could be shitty media. I've never used Sony so I can't comment on them overall, although you could have gotten a bad batch. Try #'s 1 and 2 first and let us know how it goes.
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