Make sure you have all the plugins for TCPMP installed, you can grab them from
http://picard.exceed.hu/tcpmp/test/
For the AAC plugin, just Google it. ;) There are plenty of download locations. (I'm not going to post the link here in case it's not allowed.)
The only thing I had some trouble playing were dual-audio dual-sub mkv anime files. Normal .avi's are fine.