Hello, everybody. Looks like I found a bug in date_time library when building with MinGW. I've built static boost 1.48.0 libraries under windows (Win7 64) with MinGW 3.20 (32 bit, GCC 4.6.1) with BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG option and threading=multi link=static runtime-link=static address-model=32 In this case, when using threads (-mthreads) simple operations with timings fail. I simply created a thread that slept for some milliseconds ten times next and it fails. I traced a little, it fails inside date_time functions, called from this_thread::sleep() with SIGSEGV, segmentation fault. That happens in ctor of structure simple_time_rep, out of reasons, at first glance. Looks like this structure or maybe standard time functions of MinGW are not reentrant (this is my guess, I did not dig too deep in the causes of segfault). Without flag BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG it's going all right with timings and threads. But when using precise timings and threading it fails. I also tried flags BOOST_HAS_WINTHREADS and _REENTRANT - that does not affect the case. BOOST_THREAD_USE_LIB was defined (to let it work with static libs). Is this a bug or problem of MinGW of certain version? I haven't found anything similar in bugtracker. Sincerely, Yana A. Kireyonok