So I turfed all my old Limewire files from my Mac, then I went back to the Limewire site to look for the beta 5.2.2 -- except they had a new Pro 5.1.4 version posted for Mac. Hmm. I wondered if this was the fix. I clicked on the Support tab. The clicked on the question "How do I get Limewire Pro if I've already paid?" They asked me for my email addy, then I downloaded 5.1.4. After the install, it launched. Just checked it out and it's working fine. 5.1.4 Pro seems to solve the problem.