I am failing to use XChat when behind a proxy

So I set my HTTP proxy via **Settings** -> **Preferences** -> **Network setup**, and am getting this error: Looking up irc.us.gimp.org Looking up Connecting to () port ... HTTP/1.1 502 Proxy Error ( The specified Secure Sockets Layer (SSL) port is not allowed. ISA Server is not configured to allow Proxy traversal failed. Stopped previous connection attempt (pid=4696) (` and ` are substitutions) Without that setting (the IP:PORT is left empty), I'm getting this error: Looking up irc.us.gimp.org Connecting to irc.us.gimp.org (192.219.30.200) port 6667... Connection failed. Error: Connection refused