DELPHI APPLICATION HANGS AFTER 80 HOURS MULTITHREAD ADVICE HOW TO SOLVE SEARCH??

Hi there,

our company has written an application which has a connection with another application.
This application is a TCP client program that sends TCP commands to our program.
Our program interpretes these commands and generates pulses. When these pulses are generated, an ARCNET network is scanned to see if someone interrupts this pulse. This sequence is done app. every 5 seconds. When the ARCNET message comes in, the application stops generating pulses, sends out some TCP messages to the client program and waits for another command of the client.
The pulses are generated via an hardware card and are given on our application through a DLL who scans the INTERRUPT of this card.
Next to this, there are two threads in our application, one TCP Thread and one ARCNET thread. Next to these there are app. 14 other threads generated by Delphi components who we are using in other projects.
Now to the problem. After a certain time, the application comes into the state 'Not responding'. Windows is still working fine but the application needs to be closed down with Ctrl-Alt-Del. I've inserted logging in the application to see if it the threads aren't blocking each other but everything seems fine. To call a method from within the TCP thread or the ARCNET thread we use the synchronize methods.
When the application hangs, it is the main thread that is hanging. Can anyone help me futher with this problem??
Or can anyone advice me good tools to detect the problem better?? I'm stuck with this problem for several months now and don't see a solution yet, worse, I don't know where to search anymore....
So all help, tips, tools or other things I can use to search this problem are welcome.

Here is the code of the execute methods of the self-made threads :

THE ARCNET THREAD

procedure TAtsArcThread.Execute;
var
  bStop: boolean;
  msg: S1000Message;
  iLen: integer;
  hWnd: cardinal;
  iError: integer;
  lwait: ulong;
  i, read, write: integer;
  bVerwerkt: boolean;
  str: string;
  pmsg: pS1000Message;
  lSelectResult: integer;
  UsersOk: boolean;
begin
  bStop := false;
  iLen := sizeof(S1000Message);
  hWnd := 0;
  lWait := 0; // DN 061003  was 500
  read := 1;
  write := 1;

  while (not bStop) do
  begin
    try
      read := 0;

      lSelectResult := fArc.select(read, write, lWait);

      while read > 0 do
      begin
        read := read - 1;

        iError := farc.receive(msg, iLen);

        if (SMCOK = iError) then
        begin
          farc.a_bARCOk := true;
          i := 0;
          bVerwerkt := false;
          UsersOk := false;
          syncmsg := msg;
          synchronize(GotoMainThread);
==>GOING TO MAIN THREAD

        end
        else
        begin
          if not (farc.lasterror = SMCRECEIVEFAILED) then
          begin
            farc.a_bARCOk := false;
          end;
        end;
      end;

      read := 1;
      write := 1;

      // Controleer of thread moet stoppen
      bStop := (WAIT_OBJECT_0 = WaitForSingleObject(farc.e_hStop, 0));
      if bStop then
        templog(1, 'Arcnet thread gestopt!, (WAIT_OBJECT_0 = WaitForSingleObject(farc.e_hStop, 0)) = TRUE');

    except
      on E: Exception do
      begin
        templog(2, 'Arcnet thread exception : ' + E.Message);
        read := 1;
        write := 1;
      end;
    end;
  end;

 //Zo wordt de thread beter afgesloten
 //Geen int 3 breakpoint of memoryleaks meer
 //Moet zo ongeveer, duidelijk voorbeeld in de help ontbreekt natuurlijk weer
  PostQuitMessage(0);

end;



The GOTOMAINTHREAD METHOD FOR THIS THREAD (frmclockcontroller is the main thread) :

procedure TatsArcThread.GotoMainThread;
var
  i: integer;
  bVerwerkt: Boolean;
begin
  i := 0;
  bVerwerkt := false;
  while ((not bVerwerkt) and (i < CNSARCNET_MAXUSERS)) do
  begin
    if not (farc.a_arcUsers[i] = nil) then
    begin
      if ((S1000Message(Syncmsg).hdr.cmd = ARCCMD_KOOP) and (frmClockController.ClockEngine.ClockStatus = csClockTurningDown)) then
      begin
        ErIsGekocht := True;
        frmClockController.AddException('«SMCARC MAINTHREAD» ArcNet bericht KOOP');
      end
      else
        frmClockController.AddException('«SMCARC MAINTHREAD» ArcNet bericht ONBEKEND');
      bVerwerkt := farc.a_arcUsers[i].ThreadProc(Syncmsg);
    end;
    inc(i);
  end;
end;







THE TCP THREAD


procedure TVMT.TCPServerExecute(AThread: TIdPeerThread);
// Hier komt het bericht van de VMT (tcp/ip) binnen
begin
  try
    TCPConnectionThread := AThread;

    ClientIP := AThread.Connection.Socket.Binding.PeerIP;

    while AThread.Connection.Connected do
    begin
      VMTString := AThread.Connection.ReadLn('~', 10, -1);
      Athread.synchronize(GotoMainThread);

==> GOTO THE MAIN THREAD

    end;
  except
    on E: Exception do
      templog(2, 'TCPServerExecute Exception : ' + E.Message);
  end;
end;


THE GOTOMAINTHREAD EXECUTE METHOD FOR ABOVE THREAD


procedure TVMT.GotoMainThread;
var
i : Integer;
tempstring,temp : string;
begin
{$IFDEF DNVMT}
  vmtThread.AddMessage(VMTString);
{$ELSE}
temp := vmtstring;
tempstring:='';
for i:= 1 to length(temp) do
  tempstring:= tempstring + ' '+ inttostr(ord(temp[i]));
    frmClockController.AddException('«VMT MAINTHREAD» TCP ontvangen ' + tempstring);
  TranslateReceivedValue(VMTString);
==>TRANSLATERECEIVEVALUE IS A METHOD IN THE MAIN THREAD!!!
{$ENDIF}
end;