Uninstall LW & ZA. Then reinstall LW first & after that, reinstall ZA.
http://www.gnutellaforums.com/281366-post6.html

When you uninstall LW, don't do it via add/remove programs. Start > all programs > Limewire > use the uninstall option from there

If that doesn't help, try a different version of Java (some people have had connection probs with Java 1.6.0_02). Try this version instead. Use the JRE offline installer & remove your current Java before you install this one.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

Still not connecting? Delete LW's preferences folder when LW's properly closed. See point 3 here.
Fixes for LimeWire
This will kill all of your settings within options, you'll have to go back through afterwards & reset things. If you're not sure of your settings, go through LW's tools > options & write them all down, so that you can reset things later.
LimeWire Pref Folder in Vista