Sounds like a denial of service attack to me.

Someone with nothing better to do is sitting in a irc chat room with 1000's of bots typing commands like !pingfast (insert one of voipo's many ips here)

I have been in several bot net channels. Used to run a large irc network. Had more than one guys bot net put out of commission permanently. You really should not be able to tell where its originating because they would just be infected pc's. Unless they are morons using dos software on their own pc's (most are smarter than that).

Wish they would really crack down on that stuff. The FBI seems to only focus on the people who profit from it. Good luck fighting them off.