Hello, i try to compile the *.cpp files of boost::filesystem within the following environment: os: Windows XP compiler: Visual C++ Toolkit 2003 (this is the free version of MS Visual C++ V7.1) boost: Version 1.31.0 If BOOST_WINDOWS is defined, the file windows.h is included in the sources: * exception.cpp * operations_posix_windows.cpp. Otherwise the file errno.h is included. BOOST_WINDOWS is defined within the environment mentioned above, but the compiler does not have a windows.h include file. Hence compilation fails. OTOH, if BOOST_WINDOWS is "manually" undefined, the errno constant: ETXTBSY is not defined in the file errno.h which comes with the Visual C++ Toolkit 2003. Kind regards Peter