Try deleting your LW Preferences folder whilst LW is closed; instructions here: Point #2 & 3 in Fixes for Limewire (sample image included at bottom of page.)

If that doesn't fix it. Use your add/remove control panel to remove your Java & then re-install it using the "Offline" installer which is a 15 MB downld: Java 1.5 (take the JRE)

If still problems, get the LW 4.12.0 beta http://www.limewire.com/english/content/beta.shtml