Hi there
As you alluded to, the problem inherent in MC was solved a few months ago. So that should simplify things in fixing the problem you have.
A few basic things to check under options:
Make sure 'containers' e.g. mkv are checked under video playback. I'm sure you have this.
Let's go through your filters:
- Haali media splitter is perfect. Get the latest version and install that if you don't already have it.
- FFDshow video decoder should work too. I prefer coreavc for my setup, but ffdshow still works just fine for most. I'm assuming (correct me if I'm wrong) that most of the mkv files are x264 encoded video with AC3/DTS sound.
Just having ffdshow isn't enough- it has to be configured right. Open up the ffdshow setup panel. You can do this outside MC just by going into the start menu. Near the top of the left hand sidebar in the control panel you'll see "codecs". Select this and you'll see all the codecs that ffdshow will attempt to decode. Make sure h264 is not disabled.
Again, make sure you get the latest version of ffdshow tryouts. I think the one from April 13th (?) is considered a good one.
- Sound. Install AC3filter 1.46 or ffdshow audio decoder. Make sure either one is set to decode AC3/DTS. ffdshow is more versatile. I use both for different audio codecs.
Lastly, make sure any other codec packs are disabled unless you know why each component is installed.
Hopefully this will help - either by sorting something out, or by giving you a good base for further troubleshooting.
The last thing that I can think of, and this is a longshot, would be to uninstall MC. Choose to remove the registry entries when this option is presented to you, before reinstalling the latest version. Perhaps something is not being overwritten? Make sure you don't delete your library entries and also have a library backup befoer you try this. I'm a newbie as well, so if anyone else tells you NOT to try this, listen to them.