I’m sure I’m not the only person to come across this:  release builds that die in the middle of STL somewhere at runtime after being built by Visual Studio (2005 onwards I expect).  The short answer to this is that if you have put _SECURE_SCL=0 as a preprocessor define in one project, you need to ensure that it is in all projects.  Otherwise the compiler gets confused when optimising your code because of two more slightly differing template expansions.