Thanks for the info as I am also having this problem. Unfortunately, removing the Audio/subtitle language priority does not seem to work and still results in Subtitles being displayed. I also tried the snapshot build and that appears to crash when I try to search through the folder list on the PS3.
I had the same problem with the snapshot build, I rolled back to 1.70.1 for the time being and it is working fine. Hopefully there will be another proper release with the fix applied to it.
Will try and get the debug.log but have to wait till my other half is in bed before I get access to the main TV. Also need to see if I can find a debug.log after the pms.jar file has crashed.