Unhandled error when exiting an DLL which grabs data from a database and store data into an array of structure

Hi,

Here's what I did.
I declared a structure for holding data:

#define LEN_DATA 100

struct DB_DATA
{
      char m_Username[LEN_DATA];
      char m_Password[LEN_DATA];
      char m_Submit[LEN_DATA];
};

DB_DATA* p_DBData = new DB_DATA;

Then I have 2 DLL functions for constructing and destroying the array:

BOOL EXPORTED_DLL_FUNCTION ConstructUserArray()
{

(codes ommited for database connection.. )

      SDWORD cb;
      char szUsername[LEN_DATA];
      char szPassword[LEN_DATA];
      char szSubmit[LEN_DATA];

      SQLBindCol(h_stmt, 1, SQL_C_CHAR, szUsername, LEN_DATA, &cb);
      SQLBindCol(h_stmt, 2, SQL_C_CHAR, szPassword, LEN_DATA, &cb);
      SQLBindCol(h_stmt, 3, SQL_C_CHAR, szSubmit, LEN_DATA, &cb);

      rc = SQLFetch(h_stmt);

      m_NumRecord = 0;

      while (SQL_SUCCESS == rc)
      {
            strcpy(p_DBData[m_NumRecord].m_Username, szUsername);
            strcpy(p_DBData[m_NumRecord].m_Password, szPassword);
            strcpy(p_DBData[m_NumRecord].m_Submit, szSubmit);
            m_NumRecord++;

            rc = SQLFetch(h_stmt);
      }

(codes ommited for database disconnection.. )
}

BOOL EXPORTED_DLL_FUNCTION DestroyUserArray()
{
      for (int i=0; i<sizeof(p_DBData); i++){
            p_DBData[i].m_Username[0] = 0;
            p_DBData[i].m_Password[0] = 0;
            p_DBData[i].m_Submit[0] = 0;
      }
      return true;
}

The error was generated when I was exiting the DLL.. here's what I saw from the Call Stack:

>      mfc71d.dll!CThreadSlotData::GetThreadValue(int nSlot=2012648534)  Line 269      C++

with the code:
inline void* CThreadSlotData::GetThreadValue(int nSlot)
{
      EnterCriticalSection(&m_sect);
      ASSERT(nSlot != 0 && nSlot < m_nMax);
      ASSERT(m_pSlotData != NULL);
      ASSERT(m_pSlotData[nSlot].dwFlags & SLOT_USED);
      ASSERT(m_tlsIndex != (DWORD)-1);
      if( nSlot <= 0 || nSlot >= m_nMax ) // check for retail builds.
      {
            LeaveCriticalSection(&m_sect);
            return NULL;
      }

      CThreadData* pData = (CThreadData*)TlsGetValue(m_tlsIndex);
      if (pData == NULL || nSlot >= pData->nCount)
      {
            LeaveCriticalSection(&m_sect);
            return NULL;
      }
      void* pRetVal = pData->pData[nSlot];
      LeaveCriticalSection(&m_sect);
      return pRetVal;      <------------------------------------------- Line 269
}

I tried to free the variables szUsername, szPassword, szSubmit right after the while loop but then it generates the error at the end of the free() function..

Any help is greatly appreciated..

Thanks a lot.