Here is what I have found on both Linux (an ancient version of SUSE Linux Enterprise) and Mac OS X 10.6.8 using their respective build toolchains (without any tweaks). Steps to reproduce: * Download the 2011_09_03_0448 tarball for cctbx * Replace the cctbx_sources/boost directory with the 1_48_0 release of boost * Build the Boost Test library using the default values ** ./bootstrap.sh --with-libraries=test ** ./b2 --with-test * Follow the cctbx documentation to build iotbx ** python ../cctbx_sources/libtbx/configure.py --build-boost-python-extensions=False ** source setpaths.sh ** make ** On Mac OS X, create the shared library by hand * Create a simple boost test that does nothing more than: ** Create a test function ** Create an uninitialized (or initialized if you prefer) iotbx::pdb::input variable/object in the test function This results (on both systems): An invalid free/delete for a checked array that it appears the Boost Test module is trying to free (and it was already freed by iotbx::pdb::input) This problem appears to be resolved by compiling iotbx with threads (i.e. configuring with the --enable-boost-threads flag). I'm hoping that this enabling threads will not adversely affect my python extension modules that use iotbx.pdb. Are there any issues that I should be aware of when enabling the threads for iotbx.pdb (other than Mac OS X's buggy implementations of core system components such as pthreads, polling, etc.)? --Jeff