private void DownLoad(string filepath, string filetitle) 
{
    System.IO.FileInfo fi=new System.IO.FileInfo(filepath);        
    System.Web.HttpContext.Current.Response.Clear();
    System.Web.HttpContext.Current.Response.ClearHeaders();
    System.Web.HttpContext.Current.Response.Buffer = false;
    System.Web.HttpContext.Current.Response.ContentType = "application/octet-stream";
    System.Web.HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(filetitle, System.Text.Encoding.UTF8));
    System.Web.HttpContext.Current.Response.AppendHeader("Content-Length", fi.Length.ToString());
    System.Web.HttpContext.Current.Response.WriteFile(fi.FullName);
    System.Web.HttpContext.Current.Response.Flush();
    System.Web.HttpContext.Current.Response.End();
}

------解决方案--------------------
添加这样一句话Response.AppendHeader("Content-Disposition","attachment;filename=aa.xls");  
filename=aa.xls
表示打开/保存/取消的文件名


------解决方案--------------------
友情UP


------解决方案--------------------
这个异常现象倒是没碰到过...

------解决方案--------------------
图片下载
C# code
public void SavePhotoFromUrl(string address, string FileName)
    {
        System.Net.WebClient wc = new System.Net.WebClient();
        try
        {
            wc.DownloadFile(address, FileName);
            Response.Write("<script>alert('远程文件已经下载完毕！地址为" + filename + "')</script>");
        }
        catch (System.Exception ex)
        {
            Response.Write("error:" + ex.Message.ToString());
        }
    }

------解决方案--------------------
这样一来解决了`你所描述的问题了``

------解决方案--------------------