Retain scroll position after PostBack

To keep current scroll position after postback, use some jQuery and an ASP HiddenField.

 1.) Add the HiddenField to the page:
<asp:HiddenField runat="server" ID="ScrollPosition" Value="" />

2.) Add the Javascript (requires jQuery)
       <script type="text/javascript">
        $(function () {
            var sp = $("#<%=ScrollPosition.ClientID%>");
            window.onload = function () {
                var position = parseInt(sp.val());
                if (!isNaN(position)) {
                    $(window).scrollTop(position);
                }
            };

            window.onscroll = function () {
                var position = $(window).scrollTop();
                sp.val(position);
            };
        });
    </script>