Hi, I met a crash when define _SECURE_SCL=0 in release mode but in debug mode, it's ok, I'm using VC2005. in e:\libraries\boost_1_36_0\boost\signals\detail\named_slot_map.hpp void init_next_group() { while (group != last_group && group->second.empty()) ++group; if (group != last_group) { slot_ = group->second.begin(); // crash and debugger stops at here slot_assigned = true; } } //////// code below class TestSignal { public: int counter; void OnEventReceived(char b) { counter++; } }; int _tmain(int argc, _TCHAR* argv[]) { int const times = 100000; TestSignal testSignal; boost::signal<void (char)> sig; sig.connect(boost::bind(&TestSignal::OnEventReceived,&testSignal,_1)); for(int i = 0; i < times; i++) { sig('a'); } }