Almost all the tests for the serialization system fail to link with the following message: ### mwld Linker Error: # Undefined symbol: '_errno' # referenced from 'void boost::unit_test::hrf_report_formatter::report_assertions_stat(class std::basic_ostream<char, struct std::char_traits<char> > &, unsigned int, unsigned long, unsigned long, unsigned long) (?report_assertions_stat@hrf_report_formatter@unit_test@boost@@UAEXAAV?$basi c_ostream@DU?$char_traits@D@std@@@std@@IKKK@Z)' in unit_test_result.obj (libboost_test_exec_monitor.lib) ### mwld Linker Error: # Undefined symbol: '_errno' # referenced from 'void boost::unit_test::hrf_report_formatter::report_sub_test_cases_stat(class std::basic_ostream<char, struct std::char_traits<char> > &, unsigned int, unsigned long, unsigned long) (?report_sub_test_cases_stat@hrf_report_formatter@unit_test@boost@@UAEXAAV?$ basic_ostream@DU?$char_traits@D@std@@@std@@IKK@Z)' in unit_test_result.obj (libboost_test_exec_monitor.lib) Errors caused tool to abort. To me, this suggests some issue regarding libboost_test_exec_monitor.lib . Anyone care to comment? Robert Ramey