sorry for the delay.
i disabled the joomla sef features, and the problem ceased.
it must be a conflict with the mycommunity template and the internal mosets template, as the failure of the page to load properly only happens when you choose a directory listing.
though the joomlapolis site does not appear to use the mycommunity template, i noticed they do not use sef enabled urls, and they take advantage of the mosets tree.
i figured i would follow the wise...for now.