There has been a major power outage in the US East coast, taking down Amazon Web Services and all sites that run in that service zone.
This is unfortunately affecting GrabCAD, as well, and we apologize for all the inconvenience these interruptions cause. We keep you posted as soon as the service has been fully recovered again.
UPDATE: We're all back up and running. An extra day has been added to all design challenges. Has been one very busy saturday and again, apologies for the downtime.