I've run into a really weird problem. I might be using the brush or clone stamp. Suddenly, my brush cursor turns to a standard white arrow and stays there regardless of what tool I select. True whether I use my Cintiq and pen or whether I use a mouse on another monitor. If I open a new file, the brush will work for a time before it reverts to the white cursor. My only recourse is to shut down Photoshop and restart, which is annoying as hell. My efficiency is 100%. Does anyone know what is happening? Better yet, how to correct it?