Access violation reading location 0x00000000

Call Stack:
> msvcr80d.dll!memcpy(unsigned char * dst=0x01ddfd20, unsigned char * src=0x00000000, unsigned long count=8) Line 318 Asm
Members.exe!CQueue::Pull() Line 47 + 0x18 bytes C++
Members.exe!CThreadSend::Run() Line 42 + 0xb bytes C++
Members.exe!ThreadProc(void * ipContext=0x00709be0) Line 19 + 0xe bytes C++

char* CQueue::Pull()
{
//critical open
EnterCriticalSection(&m_cs);
char* pData = NULL;
if(QueueSize() > 0)
{
MSG_Packet msgPacket;
==> memcpy(&msgPacket,m_ArrData.GetAt(0),sizeof(MSG_Packet));
pData = new char[sizeof(MSG_Packet) + msgPacket.nSize];
memcpy(pData,m_ArrData.GetAt(0),sizeof(MSG_Packet)+msgPacket.nSize);
delete[] m_ArrData.GetAt(0);
m_ArrData.RemoveAt(0);
}
LeaveCriticalSection(&m_cs);
//critical close
return pData;
}

void CThreadSend::Run()
{
char* pData = NULL;
while(TRUE)
{
if(m_pQueue->QueueSize() <= 0)
{
Sleep(50);
continue;
}

==> pData = m_pQueue->Pull();

int nPacketSize = 0;
int buffOffset = 0;
nPacketSize = GetSizePackage(pData);
do
{
int nbytesend = m_pSocketGeneral->SendMessage(pData + buffOffset,nPacketSize);
buffOffset += nbytesend;
nPacketSize -= nbytesend;
} while (nPacketSize>0);
delete[] pData;
pData = NULL;
}
}

definition m_ArrData: CArray<char*,char*> m_ArrData;

I get Access violation reading location 0x00000000. plz help me.

Thanks.

Try this:
m_ArrData.Add(new char[sizeof(MSG_Packet)]);
memcpy(&msgPacket,m_ArrData.GetAt(0),sizeof(MSG_Packet));