It seems like we are having the same sort of problem, check my recent thread:http://forums.xbox-scene.com/index.php?showtopic=693132
So far im not having a solution, but im down to 2 possible causes:
1. My current batch of Verbatim DL discs are faulty (I will soon know, since im running dry lol).
2. My burner is not up to the task of burning DL discs very succesfully anymore.
Personally im afraid that it is my burner that is the problem. Im also burning on a laptop, and i wouldn't expect those burners to be state of the art exactly. So it seems like the most likely cause :S
Good luck in finding a solution, i hope you will let me know if you figure this out. I will let you know if i do