This webpage has a redirect loop

void Session_Start(object sender, EventArgs e) 
    {
        if (Session.IsNewSession)
        {

            HttpCookie sessionCookie = Request.Cookies["ASP.NET_SessionId"];
            if ((null != sessionCookie) && !string.IsNullOrEmpty(sessionCookie.Value))
            {
                Response.Redirect("login.aspx?ReturnUrl=" + Request.Url.LocalPath);
            }
            else
            {
                return;
            }
            
        }
        else
        {
            if (Session.Count == 0)
            {
                Response.Redirect("login.aspx?ReturnUrl=" + Request.Url.LocalPath);
            }
            else
            {
                return;
            }
            
        }
}

void Session_End(object sender, EventArgs e)
   {
       if (Session.Count==0)
       {
           return;
       }
       else
       {
           Application.Lock();
           Application["UsersOnline"] = (int)Application["UsersOnline"] - 1;
           Application.UnLock();
           Session.Clear();

       }


   }