This file disappeared when the tcpdf library was updated (http://cvs.moodle.org/moodle/lib/tcpdf/html_entity_decode_php4.php?hideattic=0&view=log), but is used by the Blackboard question import format. I have removed the require_once line that was causing fatal errors for all imports, but I don't know enough to remove the 8 remaining calls to the html_entity_decode_php4 function that are still in question/format/blackboard/format.php.