I see this is a known problem (issue #1457 is closed, link at http://twistedmatrix.com/trac/ticket/1457), and the solution is to upgrade your pywin32. However, it's annoying that the current latest ActivePython 2.3 still includes the old and buggy pywin32 -- ActiveState's release notes at http://aspn.activestate.com/ASPN/docs/ActivePython/2.3/relnotes.html state that they are including build 203+ (20050128). As a simple solution, I wonder if someone could add a line to the Trac download link for the "Win32 installer for Python 2.3" saying something like: - NOTE: To avoid issues relating to launching subprocesses, please upgrade to the latest pywin32 package available at: http://sourceforge.net/project/showfiles.php?group_id=78018. If you're using ActiveState's installation then you definitely need to upgrade. Cheers, Christian