Back button issue

I use Response.Cache.setcacheability(serverandnocache) to prevent page being cached by browser.
So when user logs out properly, i will throw out user to login page. And after that if they press Back button, it will check for cookie and session value to check the login status of user.
 
This works fine in IE but not in Firefox
Anybody have an idea how to prevent displaying secured page on back button after user logs out?

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