This seems to be a problem related to apache 2 and php. (See also http://ez.no/developer/ez_publish_3/bug_reports/empty_page_after_editing_if_you_have_a_workflow_on_apache_2 and http://ez.no/developer/ez_publish_3/forum/developer/blank_page_with_ez_322_approve_workflow_and_apache_20)