Redirecting to frontpage when clicking on place order in virtuemart

[Epic Noob]

Dear folks, I'm using virtuemart version 1.1.9 and joomla version 1.5.14. My problem is that when i click on add to cart then it is taking me to the place order and continue shopping. After that whenever i'm clicking on place order button then it is redirecting me to the frontpage. The link which shows me in the place order button is:-www.mysite.com.books.html?page=checkout.index&ssl_redirect=1. I'm not using ssl in my website. Even i have changed the configuration file of virtuemart and also i checked my logged file and it is showing me  PHP Warning:  stristr() [<a href='function.stristr'>function.stristr</a>]: Empty delimiter in /home/kiranpra/public_html/administrator/components/com_virtuemart/classes/ps_session.php on line 566. I think that it is just a warning not an error. I'm using inbuilt joomla sef not any other kinds of 3rd party extensions. Any idea how to fix that?

[Joseph Kwan]

Are you sure the link is

www.mysite.com.books.html?page=checkout.index&ssl_redirect=1

This is an incorrect link.