Background: The instructor has 2 lesson activities and 1 quiz in each topic box. She is controlling access to these activities by closing topic boxes until class begins, then she opens the topic box that the class will use for the period. After the class is over she closes the topic box again until the next class time. In the grade book, the instructor enters 0.00 in activities the student's didn't complete, which then creates an override for that grade. This is correct. The next time she opens the grade book, there are overrides in grade activities for students which she didn't create. Some of the overrides appear in the category and course total. The instructor goes through the grade book and removes all overrides she didn't enter. The grade overrides reappear in the grade book sometimes within a few minutes.