Has LW worked for you before? Double check that you're only running 1 firewall & that it's configured properly
Firewall setup
If that's all ok, try updating your Java & deleting your LW preferences folder. See points 1, 2 & 3 below
Fixes for LimeWire

Otherwise you might have to look at a firewall within a modem/router. Are you running with UPnP enabled or port forwarding? Have a look through this sticky for more info
Connection problems? Check here first!