This message doesn't sound familiar. Is this the exact text that appears in your Status window? Also note that you have 3 proxy types to choose from (HTTP, Socks4, Socks5), so if one type doesn't work, try others.
it means that the irc network scanned the ip the connection was comming from for open proxies... and unfortunatly for you, it found one that it could actively abuse, and thus it disconnected you.