Thumbnails containing images causes opus crash

Almost certainly an issue with particular movie file(s) in that folder triggering a crash in either one of your installed video codecs or in the Haali Media Splitter.

There are alternative codecs & splitters which seem problem free in the FAQ on movie playback:

[HOW TO: Enable/fix playback of various media formats in Opus)

If you want to try different ones I would uninstall Haali and any codec packs first.

FWIW, I would try uninstalling Haali first, then install whichever splitters you need from the list in the FAQ and see if that solves the problem. I say that because over the years I've seen so many threads about Haali crashing that I'd suspect it before anything else. (Although I have never used it personally so maybe I'm jumping to conclusions about the quality of its code.)