Read through this sticky, it has heaps of connection & firewall info
Connection problems? Check here first!

Do you see the firewall icon? Go back through your software firewall anyway, just double check that everything's set up properly. How did you have your router set up for the old version... do you have UPnP enabled or were you port forwarding?

Do this port test & see what happens
http://www3.limewire.com:6346

If the info within that sticky's no help, post back with your details (excuse any repeat questions!)

OS(Win XP etc)
LW & Java version (help > about LW & you'll see)
Firewall you're using
Modem/router brand & model
ISP
Connection type (DSL etc)
Where you connect from (home, school etc)
Are you sharing a connection with other computers
Is this your first try with LW