I just upgraded to Snow Leopard today. I never had this problem before, I don't know if it's related. I run two displays. The Macbook Pro and an external LCD. I use a calibrator that isn't set up for dual display, so I have to unplug the external monitor to calibrate the Macbook's display. When I do, I can get the color looking pretty close to accurate. But as soon as the external display is plugged back in, the main display flickers and then the newly created profile goes bad. All the blues turn almost purple, although the whites and grays seem to stay accurate. If I unplug the external display again, the color goes back to it's corrected state. This was never an issue before the upgrade, so it seems like it could have something to do with that, but color profiling largely evades me so it's hard to say. I'm really hoping someone can help. I really don't want to have to invest in a more expensive calibration tool.