This is a strange problem. It only really happens from time to time in full screen, but its as if Ubuntu forgets how big the window is. Its being happening for a while, I just hold the alt key and move the window and it goes back to normal.

To explain it a bit more, its like the visual mouse pointer is on your screen. But the action of the mouse pointer is like an inch to the south east. It don't happen all the time, but would be good to know if anyone knows anything about it?

I have Dual monitors if that may be affecting it, and am running the propriety 338.31 nVidia tested graphics drivers on Ubuntu 14.04.