I had the same problem ... thinking about it now, it did start with 3523. An and d the damn thing was only with mkv files so, I racked my brain wondering what happened. The picture was displaying fine, but the sound was some kind of robotic stutter.
Thought I had messed up my setting so I uninstalled the whole thing, reset all my settings and tried again ... no luck
I then went to sofpedia, downloaded a full version of mplayer with smplayer. Still no luck!
I then downloaded the codecs and all of mplayer 31170, copied it on top of the mplayer version downloaded from softpedia and
yeah! it works fine now
No, idea what the problem was, but its fine now!