What causes "error C2856: #pragma hdrstop cannot be inside an #if block" in VS C++?

There was a program what I could compile under 2008 for a while. Note I can compile the program using cl and in Ultimate++ IDE. It is a fairly large program , so I am not going to post it here. I cannot compile it in Studio.

The error is

1>c:\program files\microsoft visual studio 9.0\vc\include\xstring(1735)
: error C2856: #pragma hdrstop cannot be inside an #if block

which seems to be idiotic as there is no hdrstop in there.

Precompiled headers are turned off.

This is what is there:

            if (_Mysize < _Off)
                _String_base::_Xran();  // _Off off end
            if (_Mysize - _Off < _Count)
                _Count = _Mysize - _Off;
            _Traits_helper::copy_s<_Traits>(_Dest, _Dest_size, _Myptr() + _Off, _Count);
            return (_Count);
            }

        void __CLR_OR_THIS_CALL swap(_Myt& _Right)
            {   // exchange contents with _Right <<<<<<<<----------this is the line 
            if (this == &_Right)
                ;   // same object, do nothing
            else if (_Mybase::_Alval == _Right._Alval)
                {   // same allocator, swap control information

Thanks.

Solution

Wild guess.

The precompiled headers are switched off for the project? Are they switched off for every single source file in the project (cause individual file settings overwrite whole-project settings).