Every time I try to use the tools down the left hand side of the screen Photoshop freezes. Adjustments, filters etc across the top of the screen operate and I can still save images that I have changed using those tools. I get a message that PS has detected an error in my display driver (NVIDIA GeForce GT635)and to try updating or reinstalling it. I have tried that and every other suggestion I can find on the web but each time I restart PS the 'Use Graphics Processor' is greyed out and I get nowhere. Can anyone help please?