Close LW & then check in Task Manager to make sure LW's properly closed. If there's a LW process running - end the process.

Next, go through steps 1 - 8 here (click on link): http://www.gnutellaforums.com/333278-post2.html
The link to install LW will install the latest version... make sure that you have backed up any installers of earlier LW versions that you want to save.