iSight Turns on with MB

This doesn't happen all the time but twice now, my iSight has turned on by itself when I turn on my Macbook. I went to Photobooth and the screen is just orange. Restarting doesn't work but if I shut down and turn the MB back on, it is gone.

Any ideas as to what is causing this? Is there another way to turn off the camera without having to shut down?