Hello, I have written a static library that uses boost program_options, threads, date-time and serialization libraries. There is also an extensive use of shared_ptr. I am working on a multithreaded application, so when I link my library into the executable, I use multithreaded versions of the boost libraries. When I compile my library and application that links to it, I use -pthread flag in attempt to make it multi-threaded. Everything compiles and links without a problem, however when I try to run the application, it hangs. I have tried to bedug it and when I suspend a hanging thread it gives me following stack trace: 18 _dl_sysinfo_int80() 0x003317a2 17 __lll_mutex_lock_wait() 0x0062e30e 16 _L_mutex_lock_35() 0x0062af3b 15 <symbol is not available> 0x080c80e8 14 <symbol is not available> 0x00472ff4 13 <symbol is not available> 0x080c80e8 12 <symbol is not available> 0xbffff6b0 11 <symbol is not available> 0xbffff208 10 pthread_mutex_lock() 0x0042097e 9 pthread_mutex_lock() 0x0042097e 8 scoped_lock() /usr/include/boost/detail/lwm_pthreads.hpp:72 0x080598eb 7 boost::detail::sp_counted_base::add_ref_copy() /usr/include/boost/detail/shared_count.hpp:122 0x0805b679 6 shared_count() /usr/lib/boost/include/boost-1_34/boost/detail/shared_count.hpp:216 0x0805b65b 5 shared_ptr() /usr/include/c++/3.4.6/bits/stl_construct.h:81 0x0807a7c8 4 boost::program_options::options_description_easy_init::operator() libs/program_options/src/options_description.cpp:178 0xb7fd7189 3 Settings() ../Settings.cpp:9 0x08081808 If this post sounds familiar, that's because this is my second attempt to get this problem resolved. Previously I have been told that this sounds like I've built my application with single-threading, and linked it to multi-threaded build of a boost library, or vice versa. Could you please let me know what's the right way to build my app with multi-threading. I am using Boost 1.34 libraries on Linux and compile with gcc 3.4.6 Thank you in advance for your help, Inga