Make sure they are actual Mac programs & not those for windows.
You should NOT try to unarchive a file via launching it through LW otherwise it may cause such problems as you are having. Instead, go to the LW download folder & do it from there.
Similar topics:
http://www.gnutellaforums.com/genera...-open-exe.html ______ http://www.gnutellaforums.com/genera...-dos-mode.html