异步模式上 程序运行一段时间后错误

异步模式下 程序运行一段时间后异常！
我的程序：
unsigned char SendBuffer[4] = {0x02, 0x10, 0x81, 0x6c};
定时器里发送数据：       
         OVERLAPPED m_ossend;
         COMSTAT  Cs;
         unsigned long  nwrite;
 memset(&m_ossend,0,sizeof(OVERLAPPED));
 m_ossend.hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);
         unsigned char number = SendBuffer[0];
         DWORD dwErrorFlags;
         ClearCommError(HandleCom,&dwErrorFlags,&Cs);
         if (WriteFile(HandleCom, SendBuffer, number + 2, &nwrite, &m_ossend) == 0)
         {
          if(GetLastError()==ERROR_IO_PENDING)
{
         WaitForSingleObject(m_ossend.hEvent,1000);
}
         }

线程里接受数据：
void __fastcall FR::Execute()
{

    while(!Terminated)
    {
        Synchronize(Receive);
    }
}
//---------------------------------------
void __fastcall FR::Receive()//数据接收
{
        static double count= 0;

        Form1->DisByteMemo->Text =  count;
        count++;
        unsigned char  ReceiveBuffer[512] = {0};
        unsigned long  ReceiveBufferLength = 512;
        OVERLAPPED m_osRead;
        COMSTAT  Cs;
memset(&m_osRead,0,sizeof(OVERLAPPED));
m_osRead.hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);
        unsigned long  nread;
        unsigned long Error;
        for (int i = 0;i < ReceiveBufferLength; i++)
        {
            ReceiveBuffer[i] = 0x00;
        }

        ClearCommError(HandleCom, &Error, &Cs);

        if (Cs.cbInQue > 0 )
        {
            int temp = min(Cs.cbInQue,ReceiveBufferLength);
            if(ReadFile(HandleCom, ReceiveBuffer, temp, &nread, &m_osRead) == false)
            {
                if(GetLastError()==ERROR_IO_PENDING)
{
     WaitForSingleObject(m_osRead.hEvent,2000);