Are you sure your isp doen't block p2p? Ask them. What brand name & model number of modem & router do you use? Many cable & broadband modems have a type of firewall. That means in order to use p2p, play advanced games over the net or video conferencing, you'd need to allow access for them thru a process known as port forwarding. If you can provide detailed answers I might be able to help if this is the problem.

Also, make sure you have the most recent Java: Java 1.4.2 (click on link)