I have used Contact Form 7 successfully for a while, but some time ago, while using WP 3.5.1 I found that my page editing functions disappeared when Contact Form 7 was active. I then had to deactivate the contact form so I could edit my pages, then reactivate.
I have since updated to WP 3.6
Now I find an additional problem is occurring. With Contact Form 7 active, when I click on posts, all I get is blank screen, like the screen load stops before fully loading. If I deactivate Contact Form 7 I this does not happen.