It would appear these programs do not always play nicely together. Here is what I tried and what happened.
Internal DVD drive with a DVD:
It did not play the first time I tried it. I ejected the disc, then I shut down both Passkey and Fab Media Player (completely via the hidden icons box).
Then I put the DVD in the drive and waited for the machine to accept it. Then I launched Passkey and waited for it to complete scanning the disc. Then I launched Media Player in full menu mode and it played the DVD ok. I did not let the entire disc run.
External LG BD writer with a BD:
I followed the same steps here as what worked for the DVD. Everything seemed ok until the menu items completed and I clicked "Play" in the menu and it tried to play the main feature . . then the program just went off into lala land. I tried multiple times with the same result. It did not matter if Passkey was running or not.
I shut down the programs and ejected the disc. Then I reset Media Player to "simple mode" playback (meaning it skips the menus and goes straight to what it thinks is the main feature).
Then loaded the disc, launched passkey, launched media player, waiting between each of the steps.That worked - the movie started playing.
I am confident I could easily rip either of these discs to my hard drive via Passkey.
You mentioned Media Player Classic earlier. I don't think it supports full menu mode, but can you play the main feature for these problematic titles via MPC?
Another program I use is VLC Media player . . it works well also, but not with menus.