(this is not an install problem but i don't know the proper component.) halt and shutdown try to do X things with $DISPLAY is set. this is really painful since on server machines, $DISPLAY might well be set (from a login that propagated it or something) but the machine is in trouble -- that's why you're trying to reboot it. this is unlike every other unix i know of, and it seems undesirable to me. i understand that for novice users, in x, it may be useful. so maybe there should be an alias or an option, but as default behavior ... argh. thanks.
You're probably noticing them when run through the userhelper program; is /usr/bin before /usr/sbin in root's path in your case?