통신 스레드를 생성하면서 초기화 까지 해버리니 문제가 됬나 봅니다..
         for(int i = 0 ; i < 256 ; i++)
         {
             ComThread[i] = new TComThread(this);
             ComThread[i]->Port = StrToInt(Configure->ComConfig->Cells[2][i+1]);
             ComThread[i]->Parity = pr[StrToInt(Configure->ComConfig->Cells[5][i+1])];
             ComThread[i]->StopBits = sb[StrToInt(Configure->ComConfig->Cells[6][i+1])];
             ComThread[i]->Baud =     2400;
             ComThread[i]->PacketSize = 80;
             ComThread[i]->DataBits = 8;
             ComThread[i]->Timeout = 100;
             ComThread[i]->Name = "C"+IntToStr(i);
             ComThread[i]->OnPacketReceived = ComThreadPacketReceived;
          }

생성시킨후..

for(int i = 0 ; i < 256 ; i++)
        {
             ComThread[i]->ComClose();
             ComThread[i]->ComInit();
        }

로 하니까 문제점이 없어진 듯 하네요..