Well, that second one wasn't a URL at all; it was a result from their server logs stating that my IP was connecting too much when I tried to access mchat.php.
I got another reply, and they think that it's just a matter of mChat resulting in high CPU usage and server load. I reminded the lady that I was talking to that mChat wasn't even installed on the current style, and, now that it is, guests and members can access the mChat (both on the index page and at mchat.php) without problem. And, again, the problem occurs when I try to submit an edit to a post, which has nothing to do with mChat legitimately, so we're clearly looking at some sort of faulty redirect, not an expensive module, right?
Again, I'm lost. Is there something wrong in my posting.php that you guys could check out, or would the problem be elsewhere? I'm confident enough that this has nothing to do with AutoMOD or mChat, at this point. Could it have something to do with my outdated style? I don't want to presumptuously switch over to a new one, say, "Oh, things are working, now," and find out a month later that I just moved the problem to a more critical area or something.
I suppose that this post up to the one that starts with, "After some backups, guessing, and testing," could be moved to a new thread in the support forum, if you'd be so kind.