下载25MB文件时出现问题-下载8MB文件时没有问题(ASP.NET)

我在同一个位置有两个文件,但是大文件在即将完成下载时会出错(在IE和Firefox中)。

我使用以下代码:

public static void DownloadZipFile (string filename, bool notifyMe)
{
    HttpContext context = HttpContext.Current;
    HttpServerUtility server = context.Server;
    bool ok = false;
    try
    {
        string file = string.Format ("~/contents/licensing/members/downloads/{0}", filename);
        string server_file = server.MapPath (file);

        HttpResponse response = context.Response;
        //response.BufferOutput = false;
        response.ContentType = "application/zip";
        string value = string.Format ("attachment; filename={0}", filename);
        response.AppendHeader ("Content-Disposition", value);
        FileInfo f = new FileInfo (server_file);
        long size = f.Length;
        response.TransmitFile (server_file, 0, size);
        response.Flush ();
        ok = true;
        response.End ();
    }
    catch (Exception ex)
    {
        Utilities.Log (ex);
    }
    finally
    {
        if (ok && notifyMe)
            NotifyDownload (filename);
    }
}

有什么想法吗?