[Boost-users] [statechart] - BOOST_ASSERTION in state_machine::send_event if used by multiple threads

Hello, I've several threads running. Each thread has its own state_machine. Sometime (not reproducible) I get following assertion: /opt/boost/include/boost-1_33_1/boost/statechart/state_machine.hpp:833: void boost::statechart::state_machine::send_event(const boost::statechart::event_base&) [with MostDerived = iris::proto::svc::smogx::net::ipv4::stream, InitialState = iris::proto::svc::protoogx::net::ipv4::stream, Allocator = std::allocator<void>, ExceptionTranslator = boost::statechart::null_exception_translator]: Assertion `get_pointer( pOutermostUnstableState_ ) == 0' failed. What does get_pointer( pOutermostUnstableState_ ) != 0' indicate? Regards, Oliver