This problem is mentioned elsewhere on the boards but I didn't see a clear solution. Some things that might help are to make sure you are running the latest version of MRJ, reinstall MRJ, or try the latest version of LimeWire if you haven't already. Rebuilding the desktop (command + option at startup until a message asks if you want to rebuild) may make it possible for the installer to find MRJ.

This post mentions that older versions of LimeWire worked since they used an earlier version of MRJ. That might help. The updated download link follows.

<http://www.gnutellaforums.com/showth...5933#post18023>
<http://www3.limewire.com/download/>