Current behaviour: If a student's account is deactivated, they can still log in. They receive no error message or a message notifying them that their account is deactivated. When they try to access a course that is live, they get a very confusing error message:

Then they  contact the course staff (as the message tells them to) who are even more confused, as they know their course is online and set up correctly.

The course staff also have no way of knowing if a student's account had been deactivated. They don't see the student on their student list either.

Suggestion: when a student tries to log in with a deactivated account, they should first get a message saying something like "Sorry, your account has been deactivated. If you'd like to re-activate it,...."