C++ warning: cannot pass objects of non-POD type

I know this is not uncommon error but in this case, do not see a problem. Can someone help identify the problem. The OS is CentOs 5 wit g++ 4.1.
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//Warning 1 on line 4 - warning: cannot pass objects of non-POD type ‘StdString<char, std::char_traits<char>, std::allocator<char> > ’ through ‘...’; call will abort at runtime
//Warning 2 on line 8 - warning: cannot pass objects of non-POD type ‘class stdStdString<char, std::char_traits<char>, std::allocator<char> >’ through ‘...’; call will abort at runtime


///////////////////////////////////////////////
1)try {
2)   xxx.ParseFile(z_FileName.c_str());
3)}
// Warning 1 here
4)catch(ZZZ_Exception &except) {  
5)         printf("%s File error : %s\n", m_pPrefix, except.what());
6)         return false;
7)}
// Warning 2 here
8)catch(...) {
9)         printf("%s File error : Unknown Parse File Exception\n", m_pPrefix);
10)         return false;
11)}
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12)class ZZZ_Exception : public std::exception
13){
14)      StdStringChar   _what;
15)      int            m_nCode;
16)public:
17)      ZZZ_Exception    (const StdStringChar &what_arg, int nCode=0): _what (what_arg), m_nCode(nCode) {}
18)      virtual const  char *what              () const throw()         { return _what.c_str();}
19)      virtual        int   code              () const throw()         { return(m_nCode);}
20)        ~ZZZ_Exception() throw() {}
21)};
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typedef StdString<char, std::char_traits<char>, std::allocator<char> >            StdStringChar;