when an institution's enablement expires, it should be handled, not just cause errors. what effect it *should* have isn't clear. for starters, the institution manager should probably see a notice that it's disabled and nothing more. What about class instructors or students?
my thoughts... gls and institution mananger should get emailed 2 weeks before expiration, 1 week before expiration, and 2 days before expiration. emial should include a list of any active classes this will cause problems for (though end date of class should already have been pinned to end date of institution). upon expiration, classes should become "inactive" (though i'm not sure we've hammered out exactly what that means, either ;)
*** Bug 1022196 has been marked as a duplicate of this bug. ***
Please resubmit if this is still an issue.