Solved- MPC suddenly started using Haali Media Splitter instead of LAV

I already solved it myself. For some reason, the internal filter was deactivated for Matroska files. I still don't know how that happened and why it was even worse for some files, but it doesn't really matter anymore...
______________________________
Without even changing a single setting, my setup suddenly started using Haali Media Splitter instead of the LAV Splitter it used before. I can't find any language and subtitle options in the Haali menu, so that would already be a big reason to go back to LAV. But there is a bigger problem: On some files that definitely worked just fine, I can't even get the video to play anymore (it can't find any subtitle and video streams, but the audio still works).

Why the hell did it switch to another splitter without me changing anything at all? And how can I go back to the old one?