Hi, This crash has always occurred, even since 1.34.1. It's now reproducible in 1.35. I use the following command line to build boost in such a way that Boost.Python links against the debug python libraries: bjam --toolset=msvc --layout=system link=shared threading=multi variant=debug python-debugging=on stage Note that Visual Studio 2008 is the only MSVC compiler installed on my system. I'm using Python 2.5.2. Any time I call into a Boost.Python function I get an access violation when writing to location 0x00000000. Note that I have been able to get crashes when calling the initMyInterface() function for BOOST_PYTHON_MODULE(MyInterface), I also have gotten this crash when calling into boost::list::insert(). I have no idea what the issue could be. Note that when I built Boost.Python (debug) using the visual studio project before it was removed in 1.35, it worked perfectly. Any help is greatly appreciated since this is a complete blocker issue for me.