C#此种方法导出Excel2007打不开，2003可以打开。如何解决？谢谢
 System.Web.UI.WebControls.DataGrid dgExport = null;
            // 当前对话
            System.Web.HttpContext curContext = System.Web.HttpContext.Current;
            // IO用于导出并返回excel文件
             System.IO.StringWriter strWriter = null;
            System.Web.UI.HtmlTextWriter htmlWriter = null;

            if (dt != null)
            {
                // 设置编码和附件格式
                curContext.Response.ContentType = "application/vnd.ms-excel";
                curContext.Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(strTitle, System.Text.Encoding.UTF8).ToString() + ".xls");
                curContext.Response.ContentEncoding = System.Text.Encoding.UTF7;
                curContext.Response.Charset = "";
                // 导出excel文件
                strWriter = new System.IO.StringWriter();

                htmlWriter = new System.Web.UI.HtmlTextWriter(strWriter);

                // 为了解决dgData中可能进行了分页的情况，需要重新定义一个无分页的DataGrid
                dgExport = new System.Web.UI.WebControls.DataGrid();
                dgExport.DataSource = dt.DefaultView;
                dgExport.AllowPaging = false;
                dgExport.DataBind();

                // 返回客户端
                dgExport.RenderControl(htmlWriter);
                curContext.Response.Write(strWriter.ToString());
                curContext.Response.End();
            } 
------最佳解决方案--------------------
static public void GridViewExportToExcel(Page pageParam, GridView gvParam,string fileName)
        {
            pageParam.Response.Clear();
            pageParam.Response.Buffer = true;