Try reinstalling Java. Use the JRE offline installer & remove your current Java before you install the newer version.
Java SE Downloads - Previous Release - JDK 5

Next, delete LW's preferences folder when LW's properly closed. See point 3 below (also point 2 if you've used much older versions of LW in the past...there could be a folder in both locations).
Fixes for LimeWire
This will kill all of your settings within options, you'll have to go back through & reset things afterwards

That might be all it takes...it's always a good idea to delete that prefs folder after updating or upgrading LW. If you still have probs, double check that your XP firewall is off & see if this link helps for configuring McAfee.
Port Forwarding for the McAfee Security Center

Also this one. Choose your firewall from the dropdown menu on the left & then choose configuration/features.
McAfeeHelp Technical Support