Suddenly I am unable to make any changes to old posts or pages. It go to a blank page - either post.php or page.php - when I hit the Save button. The changes are simply ignored and do not register. I tried clearing the cache but that didn't work. I am able to add new posts without a problem... just can't EDIT anything.
Any ideas on what the problem could be? I have not made any changes and after this happened I upgraded to the latest version but the problem still persists.