The problem might just be the sources you've connected or reconnected to. This is generally the reason. However, if it seems a severe issue that doesn't go away, then try deleting your LW Preferences folder whilst LW is closed; instructions here: Point #2 & 3 in Fixes for Limewire (sample image included.)
But make a note of your settings b/c once you do this you'll need to reset them next time you open LW.