I believe that Stief is correct. What happens is that after a while, I'll type a song title to search, press Search, and the search bar fails to appear and the LimeWire logo shows no activity. If I add more searches, nothing happens but finally, something "kicks" in and all the searches I've entered suddenly appear.

However, there is yet another issue; under OSX 10.4, you could see search progress as an advancing darker color on the highlighted search bar header. Under Leopard, the search bar is one color, so you can no longer tell search progress. Also, on rare occasions (I couldn't get it to happen recently) the header search bar will get out of synch with the window search result. So, highlighting the header search bar shows a search result one removed. I've heard that Leopard implements a new Java version, so I'm guessing these button issues are related to that.