Apple helped me track down the clicking sound, It was Unsanity's haxie Xsounds. Just so others might learn from my experience, here's some steps to follow: 1. login as another user. If the problem is gone, you've got a bad prefs. Problem still there, go to 2. 2. boot into Safe Mode (hold the shift key down when booting). Problem, gone? Some higher level source code OR 3rd party haxie is the problem. In my case, the haxie was Xsounds. I confirmed this by first removing the Xsounds folder from the folder Applications Enhancers. The clicking stopped. Moved Xsounds back, the clicking returned. Ron