Dear sir,
I want to check for whether an user has logged in or not. Of course that is over. What I actually want is once if the user had logged out when the user clicks on the browser 'Back' button the previous page shoulld not be shown as u have in Yahoo mail or in some secured sites. How should I implement that or check that. Please someone help me out.

Are you talking about developing a website - in ASP or PHP? Your question might be better suited in the Building Web Pages area.