I just patched my dev machine with Security Patch 9767. And enabled form key on checkout from backend. Also added the form key to my custom theme. But When I tested the checkout process it freeze on billing step. I tried to log the
OnePageController.php the result is 0
Mage::log( ((int) $this->_validateFormKey() ) , null , 'custom.log' );
Any help are much appreciated.