Just upgraded to Snow Leopard. isight light keeps coming on
    intermittently for no reason. Why?

    Every now and then the isight green light comes on for a
    few seconds, then goes off. Since none of the apps that use
    it are open, why would it be just automatically flashing
    on? Mine is a school-owned computer, so I am not the
    administrator. I wouldn't want to think someone was trying
    to watch me! So, what is going on and how do I stop it?