Problem writing to dual layer DVD

Hello, I used K3b 1.0.5 to write an iso image to a Verbatim dual layer 8.5 GB lightscribe DVD with a Samsung Model SH-S222L burner. I tried it 3 times with three DVDs and two different 7.2 GB .iso files. 

Each time the write operation was successful, but the verification failed halfway through (51%). I now regret not having saved the debugging information. I checked the files, and they are intact and readable. When I attempt to play the DVDs, however, the burner gives up reading them at approximately the same point at which the verification failed (as far as I can guess).

Does anyone have any suggestions? I think if I try again without changing anything, I'll just get the same results.

Thanks

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