Occasional memory leak of VC++ console application with system("pause")

OK. So this memory leak occurs randomly. And I tried to reproduce it in a simplified version of my original program. It's a VC++ console application with common header files for MFC.

The following is my memManager class, which originally is a image correction class that manages memory and also processes image.

typedef struct Point
{
    int x;
    int y;

}TPoint;

class memManager
{
public:
    memManager();
    ~memManager();
    void AllocMemory(TPoint **pAddr, int nSize);
    void ReleaseMemory(TPoint **pAddr);
    void ReleaseAllMemory();

    TPoint* ptsPtr;
};

memManager::memManager()
{
    ptsPtr = NULL;
}
memManager::~memManager()
{
    ReleaseAllMemory();
}

void memManager::AllocMemory(TPoint **pAddr, int nSize)
{
    if (*pAddr != NULL)
        return;

    TPoint *pTempAddr;
    pTempAddr = new TPoint[nSize];
    memset(pTempAddr, 0, sizeof(TPoint)*nSize);
    *pAddr = pTempAddr;
    return;
}

void memManager::ReleaseMemory(TPoint **pAddr)
{
    if (*pAddr != NULL)
    {
        delete[] * pAddr;
        *pAddr = NULL;
    }
    return;
}
void memManager::ReleaseAllMemory()
{
    ReleaseMemory(&ptsPtr);
    return;
}

And here is the the code in the main function.

memManager myMemManager;
myMemManager.AllocMemory(&myMemManager.ptsPtr,5000000);
system("pause");

When I debug the program, the console window shows with a prompt "Press any key to continue." And then I close the window by clicking the close button. One out of ten times, the output window of visual studio shows the following:

Detected memory leaks!
Dumping objects ->
{83} normal block at 0x000001FC942D9070, 40000000 bytes long.
 Data: <                > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
Object dump complete."
The program '[348] testForMemLeak.exe' has exited with code -1073741510 (0xc000013a). 

I found it tricky to reproduce the result. Only if I clicked the close button right after the "busy" blue circle disappeared, should I get the memory leak message.

Is it because my memory handling function isn't good enough, or because the console application refused to call the destructor of memManager when I close the console window with bad timing?

Thanks.