Aye I had the same exact problem yesterday...i tried unistalling and reinstalling but it didnt work so I just restareted the computer and everything is fine now...
first just restart if that doesnt work try reinstalling and if that doesnt work unistall lime wire completly. look at the web site 2 c if theres any updates first
Same thing happened when i installed mine a while back. U gotta disable your firewall before installing it. Once u got it installed u gotta configure the firewall to allow limewire to run without being blocked by it.