Downloaded Photoshop CC 2015 yesterday. Running WIN 7, 8gb of RAM, more than enough HD before and after installation. PS 2014 was running like a charm. With PS 2015 when working with level masks and trying to pain in certain changes, the program now shows boxes in many quadrants of the image (any image, tried several) and then as I paint, there are more marching ant boxes that appear and the effect of the painting takes much time to be seen. Almost always PS closes unexpectedly. Program just "spins." Can't use level masks the way I previously did. Going to try masking/painting some other adjustment layers and see what happens.