HttpWebRequest发出重复请求

我正在运行我的程序作为一个windows服务，我试图发送一个HTTP请求每次经过的时间(我已经设置为1分钟)。我在服务器端要做的是写一个值它从查询字符串中得到。写入文件工作，但我注意到有一些重复的值被发送?

   protected override void OnStart(string[] args)
    {
        try
        {
            eventLog1.WriteEntry("In OnStart, this is another new build 016");
            timer1 = new System.Timers.Timer(5000D);
            timer1.AutoReset = true;
            timer1.Elapsed += new ElapsedEventHandler(timer_Elapsed);
            timer1.Start();
            eventLog1.WriteEntry("This is after calling start method");
        }
        catch (Exception exxx)
        {
            eventLog1.WriteEntry(exxx.Data.ToString());
        }
    }
    protected override void OnStop()
    {
        eventLog1.WriteEntry("In onStop."); 
    }
    private static void timer_Elapsed(object source, ElapsedEventArgs e)
    {
        timer1.Stop();
        el.WriteEntry("The Elapsed event was raised at " + i);
        i++;// i  is initialized to 0
        request = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create("http://www.example.com/Test.php?test=" + i);
        request.Method = "GET";
        request.Timeout = 5000;

        try
        {
            request.BeginGetResponse(new AsyncCallback(FinishWebRequest), request);
        }
        catch (System.Net.WebException e1)
        {
            el.WriteEntry("Exception 1:" + e1.Message);
        }
        catch (System.Net.ProtocolViolationException e2)
        {
            el.WriteEntry("Exception 2:" + e2.Message);
        }
        catch (System.InvalidOperationException e3)
        {
            el.WriteEntry("Exception 3:" + e3.Message);
        }
        timer1.Start();
    }
    private static void FinishWebRequest(IAsyncResult result)
    {
        request.GetResponse().Close();
    }

我在文件中注意到的是类似1,2,1,1,3,2,2,1,1,1的内容。我看不出我的代码有什么问题。HttpWebRequest是否有可能发送重复请求?