It does seem as though Optimum Online is now using a program that detects all p2p programs & prevents them from connecting. There's many such programs but here's a couple of examples: 1. http://www.sandvine.com/products/p2p_element.asp & also 2. http://www.ipp2p.org/docu_en.html
Here's a related thread that relates to this ISP Opt' Online http://www.gnutellaforums.com/showth...threadid=49691

Generally for such problems I'd suggest a proxy but I have doubts they'd work in this case. It may be worth a try though. A Fix for those whose ISP's block Limewire pages 1 - 3 which have links to alternative instructions.

Hit the ISPs where it hurts -> in their pocket. People must stand up and switch to a new ISP if necessary. See Stief's post here for some ideas: http://www.gnutellaforums.com/showth...ion#post172994