Oh oops, it's inadvertently relying on Windows having a file type association for .ogg files, but I guess that's not always there. As a temporary workaround you could install something that associates itself with that file type (e.g. VLC, Audacity, Foobar2000...)
Sorry about that, I'll have a fix in the next release.
I figured that installing it would be enough. The installer would associate itself as the default application for .ogg files and that would be enough to fix the problem. So I guess it didn't work?
(To be specific, I believe Fleshcult is blowing up because it can't find this registry key)
HKEY_CLASSES_ROOT\.ogg\Content Type = audio/ogg
Ah, well thanks for the attempt. I've uploaded a patch (v1.26b) which I ought to work regardless of whether the registry keys are there or not.
https://www.patreon.com/posts/77850863