_CrtIsValidHeapPointer exception in multithreaded application

In my application, the main thread starts up two worker threads and
there is a strange problem.

I am not very familiar with multithreaded programming and I read lots
of documents when I write the program.
I really cannot figure it out and ask you for help.

Please forgive me for my poor English, and thanks in advance to all of
you!

------------------------------------------
How I create the threads:

class CProcesser: public CWinThread{
....
};

m_pWorkers = new CProcesser[m_nThreadNum];
for (int i = 0; i < m_nThreadNum; i++){
     m_pWorkers[i].CreateThread();
}

------------------------------------------
Error message box poped up:

 Unhandled exception at 0x7c921230: User breakpoint. (It is my
English translation.)

------------------------------------------
The following is the call stack:

  ntdll.dll!7c921230()
  ntdll.dll!7c98c943()
  ntdll.dll!7c98cd80()
  ntdll.dll!7c980af8()
  kernel32.dll!7c85e9cf()

 =D0=D01807 C
  msvcr71d.dll!_free_dbg_lk(void * pUserData=0x00d6f1c0, int
nBlockUse=1) =D0=D01132 + 0x9 C
  msvcr71d.dll!_free_dbg(void * pUserData=0x00d6f1c0, int
nBlockUse=1) =D0=D01070 + 0xd C
  mfc71d.dll!operator delete(void * p=0x00d6f1c0) =D0=D0369 + 0xc C++
  mfc71d.dll!operator delete[](void * p=0x00d6f1c0) =D0=D0383 + 0x9 C++
  RecognizeDemo.exe!CArray<CRect,CRect>::SetSize(int nNewSize=0, int
nGrowBy=-1) =D0=D0386 + 0x18 C++
  RecognizeDemo.exe!CArray<CRect,CRect>::RemoveAll() =D0=D0284 + 0x2f C++
  RecognizeDemo.exe!
CProcesser::ExtractCaption(ATL::CStringT<char,StrTraitMFC_DLL<char,ATL::ChT=
raitsCRT<char>


ATL::CStringT<char,StrTraitMFC_DLL<char,ATL::ChTraitsCRT<char> > > &
strOCRResult={...}) =D0=D0404 C++
  RecognizeDemo.exe!CProcesser::Run() =D0=D0113 + 0x2e C++
  mfc71d.dll!_AfxThreadEntry(void * pParam=0x0013effc) =D0=D0127 + 0xb C=
++
  msvcr71d.dll!_threadstartex(void * ptd=0x00d9bb20) =D0=D0241 + 0xd C
  kernel32.dll!7c80b683()

------------------------------------------

int CProcesser::ExtractCaption(CString strImgName, CString &
strOCRResult)
{

    CRECT_ARRAY arrTextRectLH;
    CRECT_ARRAY arrTextRect;
    ...
    arrTextRect.RemoveAll();
    arrTextRectLH.RemoveAll();

    return nRet;
}