ASP.NET session expired simple solution

 

Add the following code to the template.master.cs file:

        protected void Page_PreRender(object sender, EventArgs e)
        {
            HttpContext.Current.Response.AppendHeader("Refresh",
                Convert.ToString(((HttpContext.Current.Session.Timeout * 60) - 5))
                + "; Url=default.aspx?timeout=true");

        }

obviously, the value Url=default.aspx?timeout=true would be that of an informational page or  a parameter added onto the default.aspx page that when opened diplays the 'information' panel.