iSight

The webcam seems to be active (red light is flashing) but it is neither possible to activate nor to deactivate the webcam. That implies that no webcam using application is able to use it, e.g. for a video conference with Skype. By trying to use the webcam via an application the statement "another program may have it in use" is prompted. I haven't figured out what causes this bug, but it can be solved by resetting the PRAM (parameter random-access memory) of your Mac Book.