Hi, Currently with Boost 1.33.1 and Visual C++ 2005, the libraries are compiled with the default _SECURE_SCL=1 value, which means Boost *.lib and *.dll files are compiled with checked iterator enabled. When an application using Boost is compiled with _SECURE_SCL=1 too, everything is fine. However, all hell breaks loose when the application is compiled with _SECURE_SCL=0 (which is the case of our projects). The problem arises because apparently the iterator implementation and structure is different. Therefore any call to Boost *.lib or *.dll functions with an iterator passed as an argument will result in a weird and unexplained crash (I first got the problem when using Boost.Signals). Because Visual C++ 2005 checked iterators are not Standard C++ compliant, I think that it ought to be possible to disable them when compiling Boost (e.g. using an additional bjam variable in the vc-8_0 toolset?). I sincerely think that not having this option is a serious bug, as it makes Boost useless for anyone using VC2005 and having performance constraints. In the meantime, can anyone tell me how it's possible to globally define _SECURE_SCL=0 when compiling Boost 1.33.1? I tried modifying boost\config\compiler\visualc.hpp, but apparently some Windows/VisualC headers are already included before it (causing a double definition of _SECURE_SCL). Regards, Tanguy