服务不再运行

I have Windows Service.程序跳转到getFileList，然后跳转到DeleteOldBackupFiles，之后什么都没有...程序不再运行，我不知道为什么..你知道吗？我的代码示例：

protected override void OnStart(string[] args)
{
    timer = new System.Timers.Timer();
    timer.Elapsed += new ElapsedEventHandler(getFileList);
    timer.Interval = 10000;
    timer.AutoReset = true;
    timer.Start();
}
protected override void OnStop()
{
}
private void getFileList(object sender, EventArgs e)
{  
    if (!Directory.Exists(backup))
    {
         Directory.CreateDirectory(backup);
    } 
    List<string> files = new List<string>();
    try
    {
        FtpWebRequest request = (FtpWebRequest)FtpWebRequest.Create(*****);
        request.Method = WebRequestMethods.Ftp.ListDirectory;
        request.Credentials = new NetworkCredential(***, ***);
        request.UsePassive = true;
        request.UseBinary = true;
        request.KeepAlive = false;
        FtpWebResponse response = (FtpWebResponse)request.GetResponse();
        Stream responseStream = response.GetResponseStream();
        StreamReader reader = new StreamReader(responseStream);
        while (!reader.EndOfStream)
        {
            files.Add(reader.ReadLine());
        }
        files.Remove(".");
        files.Remove("..");
        reader.Close();
        responseStream.Close();
        response.Close();
    }
    catch (Exception)
    {
        //getFileList();                
    }
    if (files.Count != 0)
    {
        //timer.Stop();
        foreach (string file in files)
        {    
            //Work with XML file and give data to sql
        }
    }
    DeleteOldBackupFiles();
}
private void DeleteOldBackupFiles()
{
    string[] Oldfiles = Directory.GetFiles(backup);
    foreach (string Ofile in Oldfiles)
    {
        FileInfo fi = new FileInfo(Ofile);
        if (fi.LastWriteTime < DateTime.Now.AddMonths(-2))
        {
            fi.Delete();
        }
    }               
}

我想在删除旧备份文件后，再次运行OnStart...

 timer.AutoReset = false;