debug assertion error in threads of c++ under windows

Hi All,

This my part of the c++ program using threads in windows :

//modified by pushpa
struct structExrdDoc
{
    CExrdDoc* spDoc;
    LPCTSTR sstrFileName;

    structExrdDoc():spDoc(NULL),sstrFileName(""){}
};
structExrdDoc sp;

volatile bool running;

UINT CExcelExport::run(LPVOID p)
{
    CExrdDoc* me = sp.spDoc;
    me->OnSaveDocument ((LPCTSTR)sp.sstrFileName);
    running = FALSE;
    return 0;
}
//modified by pushpa

void CExcelExport::SaveExcelFile (CExrdDoc* pDoc, const string&
strFileName)
{
    sp.spDoc = pDoc; //modified by pushpa
    sp.sstrFileName = strFileName.c_str(); //modified by pushpa
    running = TRUE; //modified by pushpa
    AfxBeginThread(run,NULL); //modified by pushpa
    //pDoc->OnSaveDocument (strFileName.c_str()); //modified by pushpa
}

Here the line of code I have commented was taking lot of time, so I hv
tried to use threads and I am new to this.

This is the declaration in the .h file

    static UINT CExcelExport::run(LPVOID p);

After some struggle I could compile the application, but when it is
run I am getting a Debug assertion error.

debug assertion failed!
program:d:\amsa\amsa\bin\gageanalysisdlld.exe
file:wincore.cpp
line:888
for information on how your program can cause an assertion failure,
see the visual c++ documentation on asserts.

Could you please help me with this.

Thanking you in advance,
Pushpa.