1) Yes, those are all the files in that directory.
2) I'm not talking about blame, I'm trying to isolate where the problem is, and again and again, responders seem to be completely ignoring the possibility of a bug in the way paint.net handles the Effects directory.
3) Sorry, no. Disabling the Effects directory does NOT prove that paint.net is not the problem, for two reasons.
3a) As I already mentioned, I have added nothing to the Effects directory for over a year. Previous versions of paint.net did not have this problem.
3b) Is it not at all possible that the way paint.net is handling the Effects directory that could be the problem? Of course it could be.
Now, with regard to Windows 10 having to authenticate the dlls before allowing paint.net to load them, is there no way to tell Windows 10, "Hey, you already checked those ten times to Sunday. Stop checking them over and over."?