Hi Gennadiy, http://www.boost.org/libs/test/doc/usage/command_line.html states "If you got "memory access violation" message (or any other message indication fatal or system error) when you run you test, to get more information of error location add --catch_system_errors=no to the test run command line. Now run the test again and it will create a coredump you could analyze using you preferable debugger. Or run it under debugger in a first place and it will break at the point of failure." I tried adding --catch_system_errors=no to the run-command in bjam, and I tried specifying it manually on the command line. No luck. I'm using windows xp, and visual c++8. Is it not possible to break into the debugger from a unit-test? Thanks -Thorsten