I have to confirm Rock's findings on the 3 networks that I'm on.
One possibility that I can think of, other than a script, is that the network may not use standard protocols, but without the network information I have no way of confirming or denying this possibility.
Just realized that the information is in the OP's 2nd post.
From zone.ircworld.org
-> zone.ircworld.org PRIVMSG RusselB-mobile :PING 1250549830
<- :RusselB-mobile!~r.k.bairs@r98-30-29-740.commercial1.cgocable.net PRIVMSG RusselB-mobile :PING 1250549830
-> zone.ircworld.org NOTICE RusselB-mobile :PING 1250549830
<- :RusselB-mobile!~r.k.bairs@r98-30-29-740.commercial1.cgocable.net NOTICE RusselB-mobile :PING 1250549830
This confirms that the difference must be with a script being run by the OP, imo.