I have Drupal 7.14, Ubuntu 12.04, PHP 5.3.10, MySQL 5.5.24.
Somehow, any form any user submits simply takes the user back to the form, blank.
As a result, I cannot log in, search, create a new account, ask for a password reset, comment, etc. No form is working.
I deleted my browser's cookies, cleared the cache with "drush cc all". No effect.
Is there anything I can do?