procedure MyThread.Execute;
begin
 try
   { Thread-Code hier einfügen }
   if IsHostAlive(Server) = True then
   begin
     if AppStart = True then
       frm_main.lv_server.Items[id].ImageIndex := 1 //Server Online
     else
       if status = 1 then
         frm_main.lv_server.Items[id].ImageIndex := 1 //Server Online
       else
       begin
         frm_main.lv_server.Items[id].ImageIndex := 1; //Server Online
         ShowMessage('Server Online');
       end;
   end
   else
     if AppStart = True then
       frm_main.lv_server.Items[id].ImageIndex := 2 //Server Offline
     else
       if status = 2 then
         frm_main.lv_server.Items[id].ImageIndex := 2 //Server Online
       else
       begin
         frm_main.lv_server.Items[id].ImageIndex := 2; //Server Online
         ShowMessage('Server Offline');
       end;
 except
    on e: exception do begin
      // mache hier irgendetwas mit dem Fehler.
    end;
 end;
end;

procedure Tfrm_main.ServerOnlineCheck(AppStart : Boolean);
var
  Thread : MyThread;
  i : Integer;
begin
 for i := 0 to lv_server.Items.Count - 1 do
 begin
   // Anwendung aktualiseren
   Application.ProcessMessages;

   Thread := MyThread.Create(True);
   Thread.Server := lv_server.Items[i].Caption;
   Thread.id := i;
   Thread.status := lv_server.Items[i].ImageIndex;
   Thread.AppStart := AppStart;
   Thread.FreeOnTerminate := True;
   Thread.Resume;
 end;
 lbl_overview_servercheck.Caption := FormatDateTime('dd. mmmm yyyy hh:nn:ss',now)
end;