The following code will prevent the web page from being cached by the Client Browser. Use this code in pageload.
Code
Response.Cache.SetNoStore();
Response.Cache.SetCacheability(System.Web.HttpCacheability.NoCache);
Response.AddHeader("Pragma", "no-cache");
//Tell proxy servers not to cache the page.
Response.Cache.SetExpires(DateTime.Now.AddSeconds(-1));