session is maintained when browser back button is clicked

[eluser]PHPraja[/eluser]
hi all...
my problem is though i logged out from my application ie(current userid in session is destroyed) and when i click browser back button the userid in session is still maintained. with out disabling the browser's back button, is there another solution for my problem?
I want the session to be destroyed and the previous page should not be displayed.
hope my problem is clear.. me requesting for any code....

thanks in advance..