EDIT: I found the source for the problem, although it doesn't make any sense to me. I set audio to keep AC-3 tracks, but I didn't use that setting earlier, and LPCM worked just fine before.
EDIT2: And now, a week later, I found that the answer to my problems was already on the forums. Apparently my search-fu is bad.
I'm running i5 computer, 100mbit ethernet, connected via switch to the router, so it's PS3 <-> switch <-> router <-> PC.
Here's what happened:
PMS was working perfectly fine. Then we got a new router, which was somewhat brutally put in place. I got about 10 sec warning before the guy ripped the ethernet cables out, so I didn't have time to shut anything down. This didn't affect playback at the time, but afterwards, the left and right channel in the Dr. Who episodes I've started watching is non-existent. The effect is I can hear the music, I can hear the sound effects, but I can't hear the voices any more. I've also tried using a different codec (switched from MEncoder to tsmuxr), that didn't help. I tried changing the audio settings, that didn't help.
EDIT: I forgot to mention, I looked through the debug log, and it doesn't show any errors. Do you want to see it anyway?
What I've tried to do to fix the situation:
Remove PMS config
None of this helped. Do anyone have any idea what I could try to fix this? Should I try restarting the router?
EDIT: Slight update, it seems to be a problem related to 5.1 audio, but changing the settings for number of channels make absolutely no difference, nor was it a problem earlier. EDIT2: Number of channels seem to be only related to AC-3 audio, which I don't use, so never mind that bit, I use LPCM.
EDIT: The problem seems exclusively related to .mkv-files with 5.1 audio. .avi (which I assume is decoded by the PS3 itself) doesn't have this problem.