HTTP module re-writing the URL with some encryption

Question

I am writing one class with the help of HTTPModule to check userIdentity in session before he access any page.If the variable in the session is null or empty i am redirecting the user in session expired page.

Code in Class:

public class SessionUserValidation : IHttpModule
{
    public void Dispose()
 {

}

public void Init(HttpApplication application)
{
    application.PreRequestHandlerExecute += new     
      EventHandler(application_PreRequestHandlerExecute);
}


private void application_PreRequestHandlerExecute(object sender, EventArgs e)
{
    HttpApplication application = (HttpApplication)sender;
    IHttpHandler handler = application.Context.Handler;
    Page reqPage = handler as Page;
    if (reqPage != null)
    {
        reqPage.PreInit += new EventHandler(CustomModule_Init);
    }
}


private void CustomModule_Init(object sender, EventArgs e)
{

    Page Page = sender as Page;
    if (!Page.Request.Url.ToString().Contains("mySessionExpired.aspx") &&
        !Page.Request.Url.ToString().Contains("myLogin.aspx"))
    {
        if (HttpContext.Current.Session["encryptedUserId"] == null)
        {


    HttpContext.Current.Response.Redirect("../Modulenames/mySessionExpired.aspx", false);
        }
    }
}

}

everything is working fine , only issue is that its adding some kind of encryption in URL for which my Breadcrumbs are not working in the page. The url transforms like :

://thewebsite/Project/(S(jnd4o5ljdgs0vq1zd4niby4a))/Pages/mySessionExpired.aspx

no idea why this fragment of text has been added ... please help

--Attu