(It may or not be relevant that this is a Core Duo iMac) I noticed my screen seemed a bit washed out and checked the Display settings, to find that Generic RGB Profile was highlighted (I'm pretty sure that's because none are actually selected, and the generic one is highlighted only because it's the first in the list). Apart from this generic profile in the list of calibration profiles there is only one called iMac, and one called iMac Calibrated (the one I set up myself). I have "Show profiles for this display only" selected. If I select any of the profiles including the generic one, I get the "error beep" and when I close and reopen the Display settings, the generic one is always highlighted. If I select Calibrate, I get an error popup saying "Can not calibrate the display. The factory profile for the display cannot be found" (yes, it says "can not" ) . This is the second time this has happened, and I'm not sure how it fixed itself last time, but I noticed the screen like this just before the last OS update but it was ok afterwards. I'm guessing this is a preferences issue, so is there any plist I should nuke?