Have you just installed LW or has it been running ok & just now given you the error?

If it's been running ok before, try deleting your preferences (with LW closed):
http://www.gnutellaforums.com/showth...threadid=36420

If you've just installed it, uninstall & then reinstall using the Offline installer:
http://www.gnutellaforums.com/showth...threadid=50931