Haali Media Splitter is a separate application from MC. It is a very commonly used DirectShow filter that is used to extract different audio and video streams from individual AVI files (among many other media container file formats). It is included with many common "codec packs" that are available on the internet,
including the CCCP, and is generally considered to be the best splitter filter around (another is the Morgan Stream Switcher, but it causes problems on many systems and isn't as capable).
MC, as a DirectShow player application, uses the splitter if it is installed and activated on your system when playing back supported media formats. Any error messages it throws up, while they may be displayed by MC, are not specific to it. If you try to play that same file using any other DirectShow player (such as Media Player Classic or Windows Media Player) you will likely get the same result. These types of players (which most Windows media player apps are) don't actually render most media files themselves. Instead, they ask the Operating System to do so. The OS sends the file through a "chain" of different DirectShow "filters" which decode the file format, the various compression formats used, and finally render it on the screen. This is a great way for applications to be able to support a wide variety of different media types without having to "build in" support for each individual type. As long as someone has built a DirectShow filter, and you've installed it, the app should support whatever file type you throw at it (even if the app's developers have never seen the file type before). The downside is that you're depending on a whole bunch of little applications written by different people to all work properly together....
The Haali Media Splitter web site is here:
http://haali.cs.msu.ru/mkv/I suggest you download and install the most current version of the software. This might solve your problem. If not, read the FAQ available there. If you still can't figure it out, and you can successfully play the file back using other non-DirectShow methods (such as with VLC Player), you may want to submit a bug report to the
matroska.org Mailing Lists.
If, by some oddball chance, you are able to play the same file back using Media Player Classic (MPC) or Windows Media Player (WiMP), then definitely post back as it could be MC specific. This is fairly unlikely though.