The scenario is that a user may be on page 4, clicks a link, decides it is the wrong link, then hits the backbutton. The sorted list and page should be maintained. I've tried enabling viewstate, and even storing the page index into the session and having it load on prerender (if not null). What is happening is that when I hit the back button, I get an error stating that the page has expired. What is the normal practice for obtaining this effect and are there any suggestions as to why the page is expiring, preventing my ability to use the back button?