I have the strong suspicion that some Princo blank media can seriously damage your LDW-411S drive!
First of all, if your drive isn't functioning like it should, bring it back! You have warranty and even if the problem is caused by bad media, YOU HAVE WARRANTY!
And if you encounter problems with your drive after you have used Princo's, please post a reply to this thread. I want to make an overview.
To read more about the technical backgrounds of why I suspect Princo (and maybe some other brands) to kill your 411, read here