Found the issue. With IE 8 the first time you view the page there is not Page.Theme to set and there is no Cookie everything null. Once you change the format then you have a cookie to get all of you data from.
Added this code.
private string baseTheme = "DarkGrey";
private void Page_PreInit(object sender, EventArgs e)
HttpCookie preferredTheme = Request.Cookies.Get("PreferredTheme");
if (preferredTheme != null)
Page.Theme = preferredTheme.Value;
Page.Theme = baseTheme;
Now if I clear my cache and go to the page for the first time, at least as the browser believes it to be, I will default to the "DarkGrey" Theme. I briefly skimmed over Chapter 6 again and did not see anywhere that you added a default theme. If you did can you please let me know where? I may have an older copy.