I think my problem was having another mozilla.exe process. Thus, mozilla not liking to have more than one profile open at one time would launch the browser suites version of composer.
I think it would be worth noting on the composer++ page to 'dont have mozilla.exe running of the browser suite (seamonkey is more correct?) running when attempting to launch composer++'
See http://www.mozilla.org/build/win32-debugging-faq.html#twomoz
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