about serial port communication and new operator

hi group,

i got two problems
1) related to serial port communication
2) related to new operator

problem 1)i am opening the com port for serial communication
 COM1.then i am trying to communicate with device with this port.
on my computer i get a valid COM1 handle.then i have done GetComState
and SetComstate
and then i am issuing a read call on that port.
my problem is that for some time the program was running fine and then
suddenly it is not reading anything.

and ReadFile is returning 1 but the number of bytes read are zero i
have given the code below.
please help me if anyone knows about this problem.

BOOL fSuccess;
    CString Port = getPort();
    DCB dcb;

    hCom = CreateFile( Port,
        GENERIC_READ | GENERIC_WRITE,
        0, // must be opened with exclusive-access
        NULL, // no security attributes
        OPEN_EXISTING, // must use OPEN_EXISTING
        0, // not overlapped I/O
        NULL // hTemplate must be NULL for comm devices
        );

    if (hCom == INVALID_HANDLE_VALUE)
    {
        MessageBox("Can Not Open the port file","Error",MB_ICONERROR);
        return 1;
    }

        // Build on the current configuration, and skip setting the size
        // of the input and output buffers with SetupComm.

    fSuccess = GetCommState(hCom, &dcb);
    if (!fSuccess)
    {
    // Handle the error.
        MessageBox("GetCommstate failed","Error",MB_ICONERROR);
        return 1;
    }

        // Fill in DCB: 9600 bps, 8 data bits, no parity, and 1 stop bit.

    dcb.BaudRate = CBR_9600; // set the baud rate
    dcb.ByteSize = 8; // data size, xmit, and rcv
    dcb.Parity = NOPARITY; // no parity bit
    dcb.StopBits = ONESTOPBIT; // one stop bit

    fSuccess = SetCommState(hCom, &dcb);
    if (!fSuccess)
    {
        // Handle the error.
        MessageBox("SetCommstate failed","Error",MB_ICONERROR);
        return 1;
    }

    ////for reading from port

       char * buff = new char[1024];
    int j=0;
    DWORD i;
    CString GreatBuffer;
    while(1)
    {
        memset(buff,0,512);
        j = ReadFile(hCom,buff,512,&i,NULL);
        GreatBuffer += buff;
        if(i<512)
            break;
    }
    MessageBox(GreatBuffer,"GreatBuffer");
        delete [] buff;
        buff=NULL;