Could be a few things at play here, but most likely poor quality media.
That particular model of standalone DVD recorder seems to have some reliability issues -- just searching online, I've found quite a few complaints about it. It sounds like a bit of a flaky device, although I'd venture that 85%+ of the problems with discs in most cases are due to using bad media rather than the device itself. I know the Lightscribe disc was Verbatim, but what is the brand of the inkjet printable discs you used? Just as a note, Taiyo Yuden makes some very nice inkjet printable discs that are very reliable.
If the discs end up being the culprit, you can always rip all of the DVDs that don't play well on your player to the computer and re-burn them using better discs with
imgBurn.
Also, what did you mean by "quality is nothing like the Verbatim". Were you referring to the durability of the ink jet printable disc, or the actual video an audio quality of the content on the disc? If it was the latter, what issues did you observe? (e.g. image freezing or breaking up, audio problems, etc)