For several months now, I cannot read all zones (or no-zone) bluray discs anymore.
I have two discs like that (concerts), I could read them with no difficulty at all when I got the first one, then it became more and more difficult for the player to recognize the disc.
After several minutes of trials with different noise sequences from inside the tray, "unknown disc" is displayed on the screen.

I sometimes have some difficulties with audio cd too, but after some eject and reloads, it get to work.
"Almost" no problem with regular blurays.

Do you have an idea on what could be the problem ? Hardware ? Software ?

I have the BDP 7500 SL Mark I, with the last firmware (1.12 from my memory)