In the logout link button click event I have cleared the session variables. I am checking these session variables for null values at each page\'s load event. If it has the n
You will need to make sure the pages behind the login (those that can only be accessed after login) are not cached in the browser:
Page.Response.Cache.SetCacheability(HttpCacheability.NoCache);
If using forms authentication, you will also need to abandon the session and logout:
Session.Abandon();
FormsAuthentication.SignOut();
See this, this and this.