No one here can do a thing. Take it up with the IRCOPS on the network, the #help channel on the network, or e-mail the network from their website. If you know his host, you could also contact the host with the problem.
Other than that, just use a good firewall and make sure that you don't run any scripts you don't know about. Generally, you can freeze someone's computer if the person doesn't run a script or have a virus/trojan or have open ports.
