Might even be the RIAA. Is it a T3 connection?

You can filter out addresses using your filters; Tools>Options>Filters>Hosts

I might recommend you get Peerguardian: http://peerguardian.methlabs.org/pg2.html (FREE) just to be on the safe side also. See: Organisations trying to connect via Port 6346 to find out more about this.

You can try reporting it to Bitzi. Right click a search result. See Bitzi Lookup