I have problems with CS6 after upgrading to OS X Yosemite.
When opening a .CR2, .psd or .jpg in Photoshop, older pictures are shown i as a mosaic picture.
The file I want to open is not shown. If I open another file, another mosaic is shown.
If I close Photoshop and restart the Mac it is possible to open one picture, but then it happens again.
What shall I do?
Turn off GPU drawing in Photoshop and restart Photoshop.
You're hitting some well known bugs in the video card drivers on MacOS 10.10. Apple is aware of these issues, and working on solutions.