I have been having the same problems but my solution is as follows:
I tried uninstall MP 0.2.3.0 then install MP 0.2.2.0 and then again 0.2.3.0. Uninstalling 0.2.2.0 and reinstalling 02.3.0. And now it is working!!!!!!!
So this is a fix for me for now - but there seems to be some problem in MP 0.2.3.0 when installing a brand new installation.
actually the 0.2.3.0 version of MP is working fine - as long as you don't put on any SVN build. Then it stops working. (This is for making TS and WMV HDTV files playing). And the installing vsfilter and enabling it in Haili media splitter as Atarian said is what you need to got mkv files playing.
I'd spent many nights just getting RC3 to behave as I'd exptected it to so when I installed 0.2.3.0 and it ruined mkv playback of course I was upset. reverting back didn't seem like the best solution but it was the only way I could find to make things right (although still not perfect).
On as side note, prior to checking back in on this thread, earlier this evening, I was looking at my Haili settings as I was trying to get an unrelated mkv file to produce sound, I did indeed find that vsfilter, by default, was not set to autoload. I though it strange and it made me think of this MP issue. So tomorrow I intend to reinstall 0.2.3.0, reinstall vsfilter, then check Haili setting to make sure it's set to autoload. I'll let you know what happens (if I have to crawl back to RC3 again). peace.
sheesh.
I have a few files that refuse to play correctly. The vsfilter fix helped for most, but I have two 1080p mkv files that only play the audio. Any ideas?