Quicktime records a green screen
Try the following:

Turn off computer
Reboot Mac into Recovery (press and hold Command+R when you hear the chimes until a screen loads)
Select &quot;Disk Utility&quot;

Select your &quot;Macintosh HD&quot; volume on the left and press &quot;Repair Disk Permissions&quot;

Once that has finished, reboot your computer

If this doesn't work, call Apple Support