My Eyedropper has suddenly started changing all samples to white. No matter what area of an image I click it samples white, this is regardless of sample size or modifier keys. If I manually select a color with the Color Picker, and then sample an area of the image with the Eyedropper, same result, white. All of my other tools are working correctly. I tried resetting the tools, I verified my documents settings are correct, I restarted Photoshop, restarted the computer...nothing.