#1 Trash the old LimeWire Application Folder.
#2 Go to prefs and trash the folder ".limewire".
Download and install the newest LW 2.8.6.
If you have trouble with 2.8.6 version of LW then roll back to LW 2.7.13 which seems to work well for many.
http://www9.limewire.com:82/download/2.7.13/
Hope this helps.