I don't currently have access to a Windows development machine or to an old SBCL, so can't help with that.
I violated your moratorium to push a trivial refactoring and docstring cleanup, as suggested by the discussion with Daniel K.
PS: my take from Daniel K's patch is that we need to *eagerly* rather than *lazily* register the preloaded systems as loaded (including action-already-done-p bit) for the sake of already-loaded-systems and the function require-system that depends on it.
—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org Democracy is but government of the busy, by the bully, for the bossy. — Arthur Seldon, "The Dilemma of Democracy"