I had the same problem after resetting my user roles… this eliminated the permission for my id to write php code despite being admin. If this is happening, wordpress will be inserting <p> tags into your code and won’t render the PHP.
If you have somehow reset your user roles (ie permissions for user groups are definted in wp_user_roles) then try installing a backup. That database field should include something like
s:8:”exec_php”;b:1;s:15:”edit_others_php”;
If there is no reference to exec_php, that’s your problem.
I just started having this problem after installing bbpress. Except even reloading page.php remains blank.
