Serial thread problems

Here is my serial worker thread:

UINT SerialThread( LPVOID Param ) //Thread to monitor serial activity
{
  HWND hDlg = (HWND)Param;
  OVERLAPPED ovl = {0};
  BYTE chread;
  DWORD dwRead;
  DWORD dwEventMask;
  int i;

  if(!SetCommMask(hCom, EV_RXCHAR))
    AfxMessageBox("Error setting ComMask");

  while(TRUE){
    BOOL running = TRUE;
    while(running){
      if(WaitCommEvent(hCom, &dwEventMask, NULL)){
        if (!ReadFile (hCom, &chread, 1, &dwRead, &ovl)){
          AfxMessageBox("Error 1 reading comm port");
        }
        if (chread == 0x10)
          running = FALSE;
      }
    }

    for (i=0; i<33; i++){
      if(WaitCommEvent(hCom, &dwEventMask, NULL)){
        AfxMessageBox("Error 2 reading comm port");
      }
      if (!ReadFile (hCom, &chread, 1, &dwRead, &ovl)){
        AfxMessageBox("Error reading data");
      }
      Bar[i] = chread;
    }
    ::PostMessage(hDlg, MY_SERIAL, (WPARAM)0, (LPARAM)0);
  }
  return TRUE;
}

When a 10h is received the thread is supposed to read 33 more bytes to
a unsigned char string in Bar[]
I have verifyied that the 10h is received but I get "Error 2 reading
comm port" 2 times.
Please guide me.