customer login not working in magento 1.8.1

When we are upgrading the magento to 1.8.1 version there are in frontend customer login not working after the register for the account.

for that one fix is working for login to the existing account.

There are the missing the bit line of code in following file:





 app\design\frontend\default\yourtheme\template\persistent\customer\form\login.phtml
place following code to that file after the <form> tag :

<?php echo $this->getBlockHtml('formkey'); ?>

now customer login is properly working.