I just upgraded to CS6 after briefly using the trial. I worked on a project last night, and today, I load it up, and when I go into MovieClips that have timeline animations in them, the keyframes are all messed up. Many keyframes that should be dark gray (meaning they "have" some objects in them) are showing up white. If I select the contents on the stage, then the keyframe suddenly goes gray like it should be.
I have a screen shot of this and I tried reporting through the Adobe bug/feature request form, but then I got a bounced email back saying the Adobe email address was invalid. There's a thread in these forums that claims it's been like this for months!
Can you provide a screenshot and also the Flash Pro CS6 build. Try upgrading your version to the latest available one.