I had the same problem, running LimeWire 1.7 on a powermac G4, until I found a conflict with the "Contextual Menu Extension." I went into Extensions Manager, disabled that extension, restarted, and everything is great! I can click outside LimeWire, run LimeWire in the background, run other programs alongside of LimeWire - and it keeps running perfectly! Just like it should!

I thought that this extension may be the culprit when I noticed on the new LimeWire, there is an option to "disable contextual menus" under the "help" pulldown menu. Also, when LimeWire used to crash on me, I remembered that it also disabled the contextual menu feature at the same time as the crash.