Limewire won't launch
 

I am currently using Limewire Pro 4.18.1 with windows XP. I've never had trouble before, but now I'm getting a message that says "Limewire was unable to initialize and start. This is usually due to a firewall program blocking Limewire's access to the internet or loopback connections on the local machine. Please allow Limewire access to the internet and restart Limewire"
I checked the windows firewall, and it is already set to allow Limewire as an exception. Like I said, I have never had any problems running Limewire until recently. I have no idea what loopback connections on the local machine means. Can someone help?