I've helped moderate a few different role-playing sites and things of that ilk, and noticed a troubling problem at a number of them.
So, for example, users are expected to post in-character, or on specific topics.
Problem is, User A has stepped on User B's toes, and instead of awesome happy story telling time, or happy "this is a cool thing I have done to make my car more awesome" time, we have a string of posts that are just arguments everywhere, most of which barely relate to the topic of the site.
I've tried talking to the users, deleting the threads outright, and so on, but I've seen it time and time again.
What can be done to prevent this sort of thing from even being an option?