If Birdy's link above did not work for you, try this technique of reinstalling: http://www.gnutellaforums.com/333278-post2.html
Also, check your security software. eg: If you have spyware programs or similar, make sure LW is given as an exception as some spyware programs mistakenly consider any p2p sharing programs as spyware. Add an exception for LW to your firewall.