Hi there - sounds to me like you must me using a third party video card which is giving you some issues.
In the control panel of the video card (which will probably be on the bottom row of your System Preferences window) is where your video card options normally live.
In there you should find a, option for VIDEO DESKTOP. Disable it.
Video desktop sends your monitor data out to your TV/BROADCAST MONITOR so you can use it as an extra monitor for your Mac. It your case, its clashing with Color.
Let us know how you go
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Doug Suiter.
Freelance Director, Promos, Post & Creative.
LondonFCP/SydneyFCP Administrator.
Find Local FCP Operators (Sydney & London) at the FCP Talent Registry: www.FCPTalent.com