The simple code: std::string str("d:\\New folder"); bfs::path base(str);

Is causing an illegal memory access giving the following stack trace:

msvcp90d.dll!std::basic_string<char,std::char_traits<char>,std::_DebugHe apAllocator<char> >::assign(const std::basic_string<char,std::char_traits<char>,std::_DebugHeapAllocator<c har> > & _Right="*") Line 1052 C++

msvcp90d.dll!std::basic_string<char,std::char_traits<char>,std::_DebugHe apAllocator<char> >::operator=(const std::basic_string<char,std::char_traits<char>,std::_DebugHeapAllocator<c har> > & _Right="*") Line 927 C++ OK I guess a bit too trigger happy with this post. I was retesting and release works but debug doesn't... I'm guessing this is due to the fact we have iterator optimisation for release and not for debug e.g. _HAS_ITERATOR_DEBUGGING=0 For some reason debug is linking or pulling in the release library of boost, now I know that I guess it's as good as solved. Sorry for the post, hope it proves useful to someone in future. Regards, M