C# 由于searchresultcollection对象计数，Active directory超时异常

我在active directory中搜索组名时遇到此问题， 下面的链接与我的错误有关，但并没有解决我的问题

        string search = "*" + txtsearch.Text + "*";
        if (string.IsNullOrEmpty(txtsearch.Text))
        {
            search = "*";
        }
        DirectoryEntry de = null;
        try
        {

             de = new DirectoryEntry(strADPath,strUsreName,strUsrePassword);

        }
        catch (Exception ex)
        {
            LogMessageToFile("Fail to set the data for the DirectoryEntry : " + ex.ToString()+ "....Error message"+ ex.Message);
        }

        DirectorySearcher deSearch = new DirectorySearcher();



        deSearch.PropertiesToLoad.Add("objectguid");
        deSearch.PropertiesToLoad.Add("cn");

        deSearch.SearchRoot = de;
        try
        {
            deSearch.PropertiesToLoad.Add("cn"); deSearch.Filter = "(&(objectClass=group)(cn=" + search + "))";
        }
        catch (Exception ex)
        {
            LogMessageToFile("error while passing value to filter value" + ex.ToString()+"....Error message"+ ex.Message);
        }
        SearchResultCollection results= null;
        try
        {
            results = deSearch.FindAll();

        }
        catch (Exception ex)
        {
            LogMessageToFile("Fail to FindAll method :" + ex.ToString() + "....Error message" + ex.Message);
        }


        DataTable tbGroup = dsGroup.Tables.Add("Groups");
        tbGroup.Columns.Add("GroupName");
        tbGroup.Columns.Add("GroupGuid");



        if (results != null)
        {

            if (results.Count > 0)
            {

                foreach (SearchResult Result in results)
                {

                    DataRow rwGroup = tbGroup.NewRow();

                    try
                    {

                        if (Result.Properties["cn"] != null)
                        {

                            if (Result.Properties["cn"].Count > 0)
                            {

                                rwGroup["GroupName"] = Result.Properties["cn"][0];


                            }
                            else
                            {
                                LogMessageToFile("Result.Properties count less then 0");
                            }
                        }


                    }
                    catch (Exception ex)
                    {
                        LogMessageToFile("try to obtain Result.Properties :" + ex.ToString() + "....Error message" + ex.Message);
                    }
                    try
                    {
                        rwGroup["GroupGuid"] = GetObjectIdetifier(Result);

                    }
                    catch (Exception ex)
                    {
                        LogMessageToFile("Fail to get the data for GroupGuid :" + ex.ToString()+"....Error message" + ex.Message);
                    }


                    tbGroup.Rows.Add(rwGroup);

                }
                listBox1.DataSource = tbGroup;
                listBox1.DisplayMember = "GroupName";
                listBox1.ValueMember = "GroupGuid";



            }

        }