General update - many people will still see an "authentication error" when using the site from time to time at the moment. This is just a very unhelpful error that indicates a wider issue we are investigating.
This problem has not been solved, but the cause has been indentified.
The timeout suspension will remain in place until we have resolved this issue. The time frame for this cannot be estimated right now, but there is a possibility that the service will be unavailable for an extended period. (Possibly 24 hours)
Updates will follow.