asp.net导出excel的问题

VB.NET code:

private void ToExcel(Control ctl, string FileName)
{

HttpContext.Current.Response.Charset = "UTF-8";
HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.UTF8;

HttpContext.Current.Response.ContentType = "application/ms-excel";
HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + "" + FileName);
ctl.Page.EnableViewState = false;
System.IO.StringWriter tw = new System.IO.StringWriter();
HtmlTextWriter hw = new HtmlTextWriter(tw);
ctl.RenderControl(hw);
HttpContext.Current.Response.Write(tw.ToString());
HttpContext.Current.Response.End();
}




导出为以上代码，一般使用也正常，但发现有时会出现乱码，昨天一个个测试发现导出这个人时，有乱码，查看.xls代码如下去掉“甫”字一切显示正常
求解决办法，或有其他能解决乱码的导出方法。
HTML code:

<table cellspacing="0" rules="all" bordercolor="Gainsboro" border="1" id="DataGrid1" style="border-color:Gainsboro;border-width:1px;border-style:solid;font-siz