关于ie8下的下载问题 求指点》？403.10 禁止访问：配置无效

 protected void downF( string select)
        {
             string path="";
            if(select=="xls")
           path = Server.MapPath("examplexls.rar");
            else path = Server.MapPath("exampletxt.rar");
            //初始化 FileInfo 类的实例，它作为文件路径的包装
            FileInfo fi = new FileInfo(path);
            //判断文件是否存在
            if (fi.Exists)
            {
                //将文件保存到本机上
                Response.Clear();
                Response.AddHeader("Content-Disposition", "attachment; filename=" + Server.UrlEncode(fi.Name));
                Response.AddHeader("Content-Length", fi.Length.ToString());
                Response.ContentType = "application/octet-stream";
                Response.Filter.Close();
                Response.WriteFile(fi.FullName);
                Response.End();
            }


        }