You could try downloading the 'other' installer (click on the link below for info).
http://www.gnutellaforums.com/window...installer.html

Or try this link (which will install 4.16.6 again).
http://www.gnutellaforums.com/155831-post1.html

Otherwise, please go to this other forum & post your question there...the LW developers are there & since they're the ones responsible for the update warning - they should be able to fix this update problem.
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