A user reports that a course with open guest access often gets "messed up" when a guest hides some sections of the course and then leaves. The next guest user then doesn't see the entire course material. See:

http://moodle.org/mod/forum/discuss.php?d=59990

I suggest that one of the following two measures be taken:

1) The section hide/show buttons not be generated when the user is a guest, or
2) When a guest enters a course, that the database table entry for hidden sections for the guest user be reset to null.