Without being able to sit at the laptop I am wondering if they have changed some permissions
that previously allowed you to control your equiptment. If you are using it for the schools equiptment and not your personal gear I would be screaming blue murder at your IT department and explain that it did work and give dates and times when it stopped working so they can check error messages to find the change that caused the problem. If you get no response I would ask further up the food chain even if they are busy they should give you and indication that they have recieved your support request.