How are you burning these DVDs with Nero? (i.e. did you pick Data DVD or Video DVD?) For that matter, how is your burner doing when you burn regular data DVDs?

Right now, I don't have enough information to go on--there's a million different things you can do with Nero, so you need to give us more detail. That bit about errors has me concerned--you have checked the files against their md5s, haven't you?