Sorry to hear you are having issues with authentication.
We have seen this issue a number of times ourselves during testing, but it is normally an issue with the communication to the Good Dynamics servers failing. We don't actually have any control over that part of the process, and Good Dynamics normally recommend that the initial investigation on authentication issues is done through their support team. They have the ability to access logs to show what is going wrong in the communication with the servers.
I would suggest in the first instance you contact your own system admin - they should have details of the Good Dynamics support team and should be able to take it from there. Good dynamics would normally escalate the issue to us if they think there is an issue in our application.
Hope that helps.