UPDATE
[2014-04-21 13:53:19 | Lars Rohrbach]
The authentication problems stemmed from a back-end communication problem with our LDAP servers, causing secure requests to stop being fulfilled. A reboot of the LDAP proxy server has fixed the problem for now.
Our staff are continuing to investigate the underlying cause of the service interruption. Any pertinent details discovered will be reported here.
Resolved as of 2014-04-21 12:15:00