I've been using CS3. Without un-installing CS3, I installed CS6 . . . actually both 64bit & 32bit. I had several problems when running. For example, images often were not completely visible after loading . . . part of the image showed as transparent. I could duplicate the layer & all was ok, with both the new & original layers. This hasn't been a major problem, but is a nuisance & indicates that something is not right. Several features even cause "Photoshop CS6 has stopped working". Thankfully, I could always fall back to CS3 when a problem cropped up, altho' it was a pain having to save so often.
I deactivated CS6 and uninstalled (via Control Panel). I then re-installed, installed updates & re-activated . . . same problem when images load. I just re-installed, so I haven't had a chance to test other things.
I've postponed installing Lightroom4, hoping to solve CS6 problems first.
I downloaded & installed Nvidia GeForce G210 driver. Started CS6 . . . opened several JPG images . . . each was completely visible after loading. That sometimes happened before, so I'm not completely sure it's fixed . . . time will tell.
Now I have another (different problem) . . . The Type tool will not work. I get "Could not complete your request because something prevented the text engine from being initialized."
For what it's worth . . . each time I clicked to make the above Bold & italics I got a Windows Internet Explorer message "Are you sure you want to leave this page?"
EDIT . . . I rebooted (again) & everything seems to be working . . . EXCEPT the Windows Internet Explorer message "Are you sure you want to leave this page?"