In the cases where some titles aren't available, it may be that the licensing of the movie by Netflix expired between the time you queued them, and the time you attempted to watch them.
If all of the titles are unavailable, I would definitely call Netflix at 866-716-0414 to see if they can assist you with troubleshooting.
When watching Netflix instant movies they constantly stop and you have to restart or it will stop and say the title is unavalable. Have reset bd1600 player and it still does it. Very frustrating. have talked to Samsung support and Netflix and they play the blame game. Samsung Tv, wireless connection from bluray to computer. Hp computer running Vista 64 bit, CenturyLink(formerly Embarq) modem, 660 series.