found this, and it was the solution - https://discussions.apple.com/message/10737067#10737067
My father's macbook pro (running 10.6.
has a second monitor which is a mac cinema display. He unhooked his computer when he went on vacation and when he hooked it back up today, the 2nd monitor is in negative. The normal key command for this Control-Option-Command-8 or the universal access option will fix the second display but makes the main display negative (it toggles the negative). There is no documentation of this that either he or I can find. He has reset the PRAM. Unplugged the screen and hooked it back up again, and of course has restarted everything.
Can anyone help with this? Has anyone dealt with this? Im 200 miles away from him, cannot see the computer and have NO experience with multiple screens.
Thanks!!

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