I have looked for this elsewhere and can't find a previous reference. I have a 27" iMac 11.1 (2.8GHz) with an Eizo 22" as a second monitor. I have Eye-One calibrated the Eizo to exactly our print output (magazine publishing) and then used the Eye-One to calibrate the iMac to match the Eizo as closely as possible. I got them looking pretty similar. Here's the thing... I just did a software update (OSX security) which required a restart. On restart the screen is a different colour to before, distinctly more yellow. I can choose a different colour profile in System Preferences, some of which look quite blue. Any ideas whether this is a sudden hardware failure (GPU?), or perhaps a corruption of my calibrated profile has happened? Anyone else had the yellowing kick-in after a restart or upgrade? The screen has been perfect for over a year.