Some XP users have had LW problems when using Java 1.6.0_01. Try this version instead. We normally recommend the JRE offline installer but there's a Windows x64 version right at the bottom of the list. Remove your current Java version before you install this one
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

Otherwise, try the other fixes in this thread.

Fixes for Limewire when LW isn't operating as it should!