[quote name='Matt Young']That makes sense, yes. But as I said before, I know quite a few people who rent Blu-rays from Netflix regularly and have had no problems whatsoever.[/QUOTE]
Then it's quite possible that your system is VERY picky about what it reads and what it won't read then. I know it sucks, but...
Plus as I said if they mess about with their discs and buff them they they could possibly be destroying the data on the discs (since BD's aren't exactly like DVD's) by buffing into the top layer of the data on the disc.
Which is why all of your brand new stuff you own (games/movies) work flawlessly and the rental stuff is hit or miss.
Sure you might have a wonky system, but I'd chance that the media is

ed up....cause all signs point in that direction. This is regardless of what friends, family and others you know who rent BD's and their personal exp. with them.
Regardless, I hope you get a solution, but keep in mind, if they test it out and can't find something wrong, then they'll keep sending it back to you and nothing will have changed. You might just write it off and have to just use new media only on it and be content, again I know this sucks, but it might have to be something you have to learn to live with and be tolerant about.