windows service problem

Question

hai,

this is koti i was develop one windows service the mail concept behind is send a email at particular time instance i take one timer and write the code as follows

 ADDSEmailServiceEvents("Service Started at ");---->method to write log file
            TimerCallback timerDelegate =  new TimerCallback(doWork);
             // create timer and attach our method delegate to it
              serviceTimer =  new Timer(timerDelegate, null, 1000, 100);  

suppose i am write the any message in the catch block or in the onStop EVENT then after when we start the service in windows i got one message box the is figured
bellow attachments

  public void doWork(object sender)
        {

            try
            {
                Email emailObj = new Email();
                string path;//= @"D:";
                path = @"E:\EmailWindowsService\XmlDataFiles\";

                DataSet dsEmailT = new DataSet();
                DataSet dsSheDuleT = new DataSet();
                DataSet dsSmtp = new DataSet();
                DataSet dsUsers = new DataSet();
                dsEmailT.ReadXml(path + "EmailTemplates.xml");
                dsSheDuleT.ReadXml(path + "sheduleTemplate.xml");
                dsSmtp.ReadXml(path + "SmtpSettings.xml");
                int m = 0;
                foreach (DataRow dr in dsSheDuleT.Tables[0].Rows)
                {

                    #region SheduleForLoop


                    if (dr["EmailTemplateName"].ToString() == null || dr["EmailTemplateName"].ToString().Trim() == "0" || dr["EmailTemplateName"].ToString().Trim() == "")
                        m++;
                    else
                    {

                        if (((Convert.ToDateTime(DateTime.Now.ToString())).CompareTo(Convert.ToDateTime(dr["SheduleTime"].ToString())) != -1))
                        {
                            if (dr["Status"].ToString() != "Send" || dr["Status"].ToString().Contains("pending"))
                            {
                                DataRow[] emailT = dsEmailT.Tables[0].Select("id=" + dr["EmailTemplateName"].ToString().Trim());
                                emailObj.UserName = emailT[0]["UserName"].ToString();
                                emailObj.Password = emailT[0]["Password"].ToString();
                                emailObj.Port = Convert.ToInt32(dsSmtp.Tables[0].Rows[0]["PortNo"]);
                                emailObj.HostName = dsSmtp.Tables[0].Rows[0]["Host"].ToString();
                                emailObj.FromAddress = emailT[0]["FromAddress"].ToString();
                                emailObj.Subject = emailT[0]["Subject"].ToString();
                                emailObj.Body = emailT[0]["Body"].ToString();
                                dsUsers.ReadXml(path + "users.xml");
                                #region userForLoop
                                int i = 0;
                                foreach (DataRow user in dsUsers.Tables[0].Rows)
                                {
                                    i++;
                                    dsUsers.WriteXml("E:\\userS.xml");
                                    if (user["UserId"].ToString() == null || user["UserId"].ToString().Trim() == "0" || user["UserId"].ToString() == "")
                                        i++;
                                    else
                                    {

                                        if (Convert.ToBoolean(user["isActive"]))
                                            emailObj.ToAddresses.Add(new MailAddress(user["EmailId"].ToString()));
                                    }

                                }
                                #endregion
                                emailObj.sendEmail(true);
                                dr["Status"] = "Send";
                                //ADDSEmailServiceEvents("mail Send ");
                            }
                        }
                    }

                    dsSheDuleT.WriteXml(path + "sheduleTemplate.xml");
                }
                    #endregion


            }
            catch (Exception ex)
            {
                //string local_strMsg = "Problem in service at starting stage";
                //ADDSEmailServiceEvents("exception: " + ex.Message);
            
            }
        }

what is the problem with my webservice