Try uninstalling LW (start > all programs > Limewire & use the uninstall option, don't uninstall via add/remove programs) & ZA. Now reinstall LW. Once that's installed, reinstall ZA. It's worked for a few people
http://www.gnutellaforums.com/281366-post6.html

If that doesn't work, try using this version of Java. Download the JRE (Java Runtime Environment) offline installer & remove any other Java versions before you install this one.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

If you're still stuck, could we please have some more info?
System details - help us to help you (click here)