Video splitter is built in windows. It is called quartz.dll. When other splitter is registered, this one get unregistered. Matroska splitter won't split avi files, just .mkv files. SO, try to re-register quartz.dll (you'll find many posts about how to do this) and install codecs\filters needed
http://forum.bsplayer.org/viewtopic.php?t=3042