Weird UTF-8 characters appearing in editor. Database is fine.

I have a strange issue with WordPress 3.3.1 where the editor displays accented characters as the ? character, like when you are using the wrong encoding.

However, this problem strictly happens in the editor; The excerpt and all the rest of the site looks just fine. Even with all plugins deactivated, even after re-installing WordPress, I still have the problem. It happened for no reason at all.