Occasionally, my 15" PB (running 10.3.9) exhibits an odd behavior when I pull down the manu items from the manu bar by clicking, for example, apple sign, Finder, File, Edit, and etc. Even though I am not moving the mouse, each item in those pull down manus are highlighted one after another (ie. it looks there is an invisible mouse which is moving from the top manu item to down). It only runs once from top to bottom. But, if I click the menu item again, it does do the same thing. Has anyone experienced this odd problem with your Mac?