Let's start with a simple possibility. "No firewall" on your machine is an interesting assertion. All MACs come with a firewall in the software bundle. Open System Preferences and check what setting you have in Sharing under the tab "Firewall". For Limewire and the other p2p packages to work properly, you have to open port 6346 in the firewall. If I have misremembered the format of System Preferences under OS10.1.2, I apologise. To gather evidence on whether the firewall on your OS is the problem, try switching it off for a while. If this does not work, report back and we'll offer further advice.