Your drive is most likely just fine.
LONGTEN is very bad media (as bad as Princo, I'd say), and it is not uncommon for the quality to vary from batch to batch or from disc to disc. So the fact that you switched to a new batch probably was the cause. My guess is that in the past, you got lucky and got good batches of LONGTEN, but now, you've gotten a bad batch. Most batches of LONGTEN, and all drives (not just your LiteOn) will have problems burning to this poor media type.
Don't blame your drive for bad media; if you get a replacement, it'll have the same problem. Use better media, and you'll be fine.