Using Moodle 2.1.
In one of our courses, the instructor and all students are no longer able to view the course home page. All they see is a blank white page. If they access activities in the course directly from their MyMoodle page, the activity displays correctly, as do any other pages *except* for the home page.
The home page displays correctly for me as the administrator.
This course also cannot be backed up without encountering an error about "error/activity_task_coursemodule_not_found".
Thanks for any ideas or suggestions.