I assume you deactivated all plugins as well? Are there issues on the front end as well? or just admin/post editor.?
Someone else just posted the same issue.
updated-now-cant-edit-anything
I suggested a new, sperate install of Wp and adding your current theme to it to see what happens. You could revert to a previous version but you risk security issues. Hopfully a solution will emerge. You might try to stay in touch with this user in case they find a solution.
it is just the admin side that is effected, the visual of the site is as it should be.
I suppose you should try this too:
“Try re-uploading all files & folders – except the wp-content folder – from a fresh download of WordPress.”
Also make sure you try a theme that’s stable and up to date, twenty eleven or twenty ten, just to see if it’s your theme.
I’ve tried those themes and it still doesn’t work
install a new, seperate WP 3.3. Leave everything default and see if you can edit posts.