I'm going to ask a couple of questions that might or might not be it, but to kind of help narrow down what your problem could be. I know it's a PSD file and this usually only happens if you're working with an image of the Internet, but is the image mode set as index? You can check this by going to Image>Mode> and then selecting the mode type (RGB if you're working Internet, CMYK if you're printing). Second question, do you have Extras selected? Find out by going to View>Extras which is about 2/3's down the menu. My last question, have you tried creating a new image and working with it? Can you do that or is it just when you open a PSD file?