It's the weirdest thing.
I have not changed my recording software, or anything about Hitfilm Express from this morning when I was editing things.
My files are recorded in AVI format.
I try importing media, and it comes up in the Editor tab as 'Load Error'.
I have tried importing copies of files that are already in the editor, those will load in fine.
I have tried opening files that were created the same time as ones already in it that worked at the time (and were created the same time as the ones that do work), and they don't work.
I've googled trying to find a solution to this problem, (as I try doing before I post here always) and have not found a fix, or reason.