You know how you draw on it, and it usually covers the whole surface area of your screen? It does that, except..not in photoshop..like all of a sudden my canvas size shrunk. I'm so aggrivated, and I don't know how to fix it.
I have had a similar problem with mine. My solution to the problem was I brought it to the IT at my school and they fixed it for me(after re-imaging my computer)