Block user in the sense of "user can no longer send PMs or leave VMs to me" - yes. 
	Hiding all posts by said user - preferably not, that leads to some threads being horrible mangled messes (just imagine you two accidentally joining the same RP...). If someone is being disruptive on public forums, mods.

	On another note - did this new forum ever have e-mail notifications? It appears some people in a RP I'm in appear to be missing those, which occasionally leads to some goose-hunts.