Hello, I think the behavior of the std::string is just an example but in my application it seems to me the first stl element that is used. I have a larger project working with CLR in MC++. I included boost, because of boost::thread. Because auf the .net and CLR linking I compiled boost als shared libs and included BOOST_DYN_LINK in the preprocessor definitions. Compilation works fine. If i start the application in Debug mode i get strange behavior of my strings which results in a crash. For example an assignment like std::string test = "123"; will result in a string representation with additional malformed signs in front of the "123". I knew some behavior like this because of the Flags: #define _HAS_ITERATOR_DEBUGGING 0 #define _SECURE_SCL 0 #define _SCL_SECURE_NO_WARNINGS I usually not using them, but i have the suspicion that boost is using them and i got errors from there. Has anyone an idea what are possible solutions? Is boost introducing additional Macros that were changing the stl? Greetings Simon Adler