It's hard to say. (how the panels are arranged or any number of things)
Could you post a screenshot of each of the versions showing the difference?
"Could you post a screenshot of each of the versions showing the difference?" - There's nothing to see. In every other version of PS I've had since 1994, files opened up at decent viewing size (like 100% for a 600 x 600 px image). In this version, everything opens up at .0625% - so its being viewed at about 1x1 px.
We don't know that, but anyway what operating system and version?
Are you on a Mac or PC? If the former, do you have the Application Frame visible?
Could you post a screenshot of how Photoshop CS6 looks when you first open an image and have it show at the tiny size?
Chances are you've made the main Photoshop window small, which is causing it to try to fit a newly opened image in too small a space.
I'm going to make a wild guess that you're on a Mac, and have dragged the bottom edge of the Photoshop window up instead of turning off the Application Frame, so as to be able to see your desktop.
You were dead on, Noel. I went to the Window menu and deselected Application Window. Free at last!