soz have never used msn chat but this is what it has to say about banning under the help section
Hosts:

If a member has been especially disruptive in your chat room, you can ban them for a set period of time.

Make sure you are in your chat room.
In the member list, right-click the nickname of the member you want to ban.
Click Kick, and then click Custom Kick/Ban.
Type the reason for banning the person, click Ban for, and then choose an amount of time on the drop-down list.
Click OK.
The member will be automatically disconnected from the chat room, and a message will appear in the conversation pane noting who was banned, why, and for how long.
check out the help section for yourself its on the main chat room page

v_Ln