Hi!
Probably there's just a single connection on this IP address (one house, school or small company). Usually in this case the various users have different but similar IP addresses.
It actually does not seem to be a floating IP, neither a political thing. He simply drops in meaningless chars instead of the original page, or redirects the page to the english edition (which does not work), his style seems to be pretty stable. So you are likely to be right. It's a unique IP. Let's block it.
You will have to ask a Steward to make one (or more) of you a sysop. They then have the ability to block an IP address, which means that no edits can be done from that address.
Yeap! I've asked for it some 10 days ago :) Still waiting for an answer :) I hoped that maybe there could be someone with that access here, and that they could terminate the guy for us, while we wait for operative indipendence :)
Bèrto