onDraw goes crazy

void CNavionicsView::OnDraw(CDC* pDC)

{
    //TRACE("OnDraw\n");
    CNavionicsDoc* pDoc = GetDocument();
    ASSERT_VALID(pDoc);
    // TODO: add draw code for native data here
    int iwkViewOptionApplied=0;
    try
    {
        if (m_CEChartViewAttached !=NULL)
        {
            ...

            int iViewSizeX =m_CEChartViewAttached->GetViewSizeX(); 
            int iViewSizeY =m_CEChartViewAttached->GetViewSizeY();

            if (m_ToBeRedraw == true)
            {            
                int iSysMetricsX = GetSystemMetrics(SM_CXSCREEN);
                int iSysMetricsY = GetSystemMetrics(SM_CYSCREEN);
                if( theApp.GetTraceLevel() & (1 << (TRACE_VIEW-1)) ){
                    CString s; s.Format("CNavionicsView::OnDraw: iSysMetricsX=%d, iSysMetricsY=%d\n",
                        iSysMetricsX, iSysMetricsY);
                    OutputDebugString(s);
                }         

                m_MemDC.SelectObject(&m_Brush);
                m_MemDC.PatBlt(0,0,iSysMetricsX,iSysMetricsY,PATCOPY);
                
                BeginWaitCursor(); // display the hourglass cursor

                TRACE("OnDraw: m_CEChartViewAttached->Draw...\n");
                m_CEChartViewAttached->Draw(m_MemDC.m_hDC);
                TRACE("OnDraw: m_CEChartViewAttached->Draw: Done!\n");

                EndWaitCursor(); // display the hourglass cursor

                if( theApp.GetTraceLevel() & (1 << (TRACE_VIEW-1)) ){
                    CString s; s.Format("CNavionicsView::OnDraw: iViewSizeX=%d, iViewSizeY=%d\n",
                        iViewSizeX, iViewSizeY);
                    OutputDebugString(s);
                }


                //Devo disegnare i marker su m_MemDC così ogni copia conterrà già i marker 
                //e rotte così non dovrò più ridisegnarli.
                CNChartView::DrawMarkers(&m_MemDC);
                CNChartView::DrawRoutes(&m_MemDC);
                CNChartView::DrawAreas(&m_MemDC);
                if(theApp.m_bDrawReticolo)
                    CNChartView::DrawParalelMeridian(&m_MemDC);

                m_MemDC2.BitBlt(0,0,iViewSizeX, iViewSizeY, &m_MemDC, 0,0,SRCCOPY  );
                CNChartView::OnDraw(&m_MemDC2);

                if(m_bViewNocturne){
                    Graphics gx(m_MemDC2);//pDC->m_hDC);
                    SolidBrush blackBrush(Color(180,0,0,0));
                    gx.FillRectangle(&blackBrush,0,0,iViewSizeX,iViewSizeY);
                }
                
                pDC->AssertValid();
                pDC->BitBlt(0,0,iViewSizeX, iViewSizeY, &m_MemDC2, 0,0,SRCCOPY  );

            
#endif
                m_ToBeRedraw = false;
            }
            else
            {
                if( theApp.GetTraceLevel() & (1 << (TRACE_VIEW-1)) ){
                    CString s; s.Format("CNavionicsView::OnDraw: BitBlt\n");
                    OutputDebugString(s);
                }

                m_MemDC2.BitBlt(0,0,iViewSizeX, iViewSizeY, &m_MemDC, 0,0,SRCCOPY  );
                CNChartView::OnDraw(&m_MemDC2);

                if(m_bViewNocturne ){
              
                    Graphics gx(m_MemDC2);
                    SolidBrush blackBrush(Color(180,0,0,0));
                    gx.FillRectangle(&blackBrush,0,0,iViewSizeX,iViewSizeY);
                }                

                pDC->BitBlt(0,0,
                            iViewSizeX, //m_CEChartViewAttached->GetViewSizeX(),
                            iViewSizeY,    //m_CEChartViewAttached->GetViewSizeY(), 
                                &m_MemDC2,0,0,SRCCOPY);
            }

        }
        
    }
    //catch the exceptions here
    catch(CNavionicsException CNEwkNavionicsException)
    {
        //check if its a fatal error
        int iwkErrorNumber
            = CNEwkNavionicsException.GetErrorNumber();
        if(iwkErrorNumber>=9000  && iwkErrorNumber<=9900)
        {
            //fatal error, therefore display
            string swkErrorText;
            CNEwkNavionicsException.MessageFormatted(swkErrorText, false);
            MessageBox((swkErrorText.c_str()), "Fatal Error", MB_OK || MB_ICONEXCLAMATION);
            abort(); //exit
        }
        else
        {
            //for debugging display warning
            int iwkErrorNumber
                = CNEwkNavionicsException.GetErrorNumber();
            //fatal error, therefore display
            string swkErrorText;
            CNEwkNavionicsException.MessageFormatted(swkErrorText, false);
        }
    }

...