[boost] boost::filesystem problems under windows

hi there, I'v some trouble with filesystem::path manipulation with boost release 1.31 / vc 7.1 . The code ----------- fs::path src = fs::path(__FILE__, fs::no_check); std::cout << "src= " << src.string() << std::endl; fs::path dir = src.branch_path(); std::cout << "script dir= " << dir.string() << std::endl; ----------- generates the output src= C:\cygwin\home\stefan\ToolBox\test\scripting\Algo\embedding.cpp script dir= C: i.e. it appears path::branch_path() doesn't work. Does anybody have an idea what's going on here ? Thanks, Stefan PS: oh, and if I replace the fs::no_check above by fs::native, I get an exception 'invalid path' which, I assume, fs::native is supposed to suppress.