Addslashes is missing on line 30 in http://moodle.cvs.sourceforge.net/moodle/moodle/mod/quiz/format/multianswer/format.php.
When the ' sign is present in the question, Moodle writes Could not insert new question! error and does not insert the question into database.
original line 30:
$thequestion->name = $lines;
corrected line 30:
$thequestion->name = addslashes($lines);
It would be nice to have the questions name limited to e.g. 30 characters, it can become very long now.