My apologies to the LW community. It seems that the "whatisnexoxo" worms are already well know and seem to be totally separate from LW itself. Although I do still think it should be easier to block these invaders, one frienldly guru named Birdy showed me this link:

http://www.gnutellaforums.com/open-d...-limewire.html

Very, very helpful. But like all viruses, it needs to be updates regularly. So, many thanks, at least I have a weapon to fight with now.