A victory before lunch. I was fighting with the website, particularly registration. It suddenly decided, without saying so anywhere, that an administrator now had to approve new users, and that notifying either the administrator or the user was optional. After registering, a user couldn't understand why they weren't allowed in, tried different options, and eventually received a 9,900-hour ban for too many attempts. Lovely. Well done!
In short, I fixed it, but it cost me five precious hours. That's how it goes...