Hi! So I am using photoshop (14.2.1x16) on a macbook pro. All the sudden my brushes are not working: White is black, black does not work at all, and if I paint over the same area twice, it creates this were effect where it reverts the center but leaves the edges (think of it like running your finger through a dry-errase mark). this happens even when not using a mask. I have reset the brushes and nothing is changed. Ideas?