simple explanation
back in the day when cdr's +cdrw's were the medium, burners also had problems reading certain types and brands. This was due to exotic die process, layering, and coating. This also applies to dvdr discs. There are many review sites on the Net that test dvdr drives and such. In these tests, different brands of medium are used and tested. It would be advisable to check one of these sites out to figure out which dvdr media brands are ideal for your burner, and which to stay away from- for your certain dvdr model. By the way, the different types of dvdr media also have different reading and write rates (slower/faster- with timed values).
So Google it to read more about it 'cause it's your problem, and not mine.. But a common problem nevertheless.
Most aftermarket buyers know this type of thing already, but since your dvd'r drive was preinstalled, you didn't have much of a choice and you were probably all excited about getting it....
Are you still?