Normally when a new version is installed, it removes the previous version at the beginning of the installation process, so there's no need to remove older versions yourself.
I hope you did not attempt to remove the older version using the Add/Remove control panel because that WILL cause problems. If you did, then use this little utility to help clean up the system: Crap Cleaner

Also, delete 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 using Vista then see http://www.gnutellaforums.com/genera...der-vista.html