Can't do a cast (from my own class to a global scope function)

Hello,
Can't do a cast from CMyApp::operatorProc to global scope _beginthread... I
really want the operatorProc to live inside CMyApp... cos it would be
cleaner...
Do I need a wrapper? Would anyone help me fix this little stub? I tried
static_cast, reinterpret_cast and dynamic_cast to no avail...

======================================
void CMyApp::CallThread(int ThreadType)
{
 if (ThreadNr < MAX_THREADS) {
  switch (ThreadType) {
   case OPERATOR:
    _beginthread( reinterpret_cast<void (__cdecl *)(void
*)>(CMyApp::operatorProc), 0, &ThreadNr); <<<<<<<<<<<<<<<
    break;
   case CB:
    //_beginthread( &CMyApp::CBProc, 0, &ThreadNr);
    break;
   default:
    ;

  }
  ThreadNr++;
 }
}
========================================

c:\documents and settings\luckie\my engine version
2\gamedemo\cmyapp.cpp(290) : error C2440: 'reinterpret_cast' : cannot
convert from 'overloaded-function' to 'void (__cdecl *)(void *)'
1> None of the functions with this name in scope match the target
type

========================================
Compiler : VS2005

Thanks in advance
Jack