I really don't think it's a Mac OS issue because I've tried on different iMacs and the same thing happens, so yes of course it is a problem on Mac computers, but it is a Photoshop issue, because it always and only happens when I work in Photoshop. How can it be a Mac issue if I have never had a problem like this, but it happens everyday when I open Photoshop? It has to be a PS issue.