C / C++ / MFC

class MyBaseEvent : public CEvent
{
 public:
	 MyBaseEvent();   // contructer
         // CSingleLock mylock;
       MyBaseEvent(BOOL own, BOOL reset, LPCTSTR mystring, LPSECURITY_ATTRIBUTES mysec);
	    char *buffer_ptr;
         int len;
                CWnd *send_window;

};

LRESULT CprogDebug::receive_tcpip(WPARAM mywparam,LPARAM mylparam)// CprogDebug message handlers
        {
		UNREFERENCED_PARAMETER(mywparam);
 
        char *hold_ptr;
        CHERC_CMDApp *main_app;
        MyBaseEvent* myeventptr;
.
.
.
.

         myeventptr->send_window = this;
       myeventptr->SetEvent();              // SHOW THE WINDOW
        return TRUE;

}

   UINT hercgui_commands(LPVOID lparam)
 {
 int i;
 CString storstrg;
 BOOL bresult;
 UNREFERENCED_PARAMETER(lparam);
 void SetThreadName( DWORD dwThreadID, LPCSTR szThreadName);
 CMutex mymutex(FALSE,"HercLock",NULL);
 CSingleLock HercLock(&mymutex);
 DWORD dwbytestoread;
 CHERC_CMDApp* main_app;
 CMainFrame *main_window;
 dwbytestoread = 1500;
 MyBaseEvent *my_event;


 main_app = (CHERC_CMDApp *)AfxGetApp();


  my_event = main_app->mybaseeventptr;

  SetThreadName(GetCurrentThreadId(),"HercGUI");

 // CSingleLock *HercLock = static_cast<Mythread *>(lparam)->HercLock;

    while(1)

         {


 WaitForSingleObject(my_event->m_hObject, INFINITE);
  if (!HercLock.IsLocked())
 {
         HercLock.Lock(INFINITE);


          WriteFile(main_app->filehdl,
                       (LPCVOID)my_event->buffer_ptr,
                        30,
                        NULL,
                        (LPOVERLAPPED) &main_app->herc_over);



  }


   bresult =    ReadFile(main_app->filehdl,
                   (LPVOID) my_event->buffer_ptr,
                    dwbytestoread,
                    NULL,
                     (LPOVERLAPPED) &main_app->herc_over1);

//  WaitForSingleObject(herc_over1.hEvent,INFINITE);
 WaitForSingleObject(main_app->herc_over1.hEvent,INFINITE);


     HercLock.Unlock();
// strncpy(&stor_buffer[0],&buffer[0],100);

        my_event->send_window->SendMessage(WM_HERCGUI_MESS,(WPARAM) my_event->len,(LPARAM) my_event->buffer_ptr);    // statement casing the exception

     i = 1;
         }
   return 0;
 }

ForNow wrote:

Maybe the problem is passing pointer objects across threads ?