Wait a sec, I have an idea what could cause the GUI freeze. Do you have the bug reporting option set to always send? If not, set the config to always send.

Currently under OS X LimeWire does produce an out of memory bug every once in a while (actually quite often for me) that does not appear to impact operation much. But if the bug report is not send, it will popup a dialog box asking for what do. These dialog boxes will stack up and lots of them will make the OS X gui so slow as to appear frozen. Check if setting the bugs setting to always send fixes your freeze. if yes it is the stacking dialog problem.