Can't logon Cognos

[Janine]

We are getting the following error when trying to log on Cognos:

1 CAM-AAA-0012

An unexpected error occurred when the document 'authenticateResponse' was parsed.

CAM-AAA-0159 Document '' is an invalid XML document.

The main XML document cannot be empty.

The datasource is tested successfully. We did try to "Renew my credentials" under preference menu, but still getting the error.

could somebody shed some light on it?

[Garnio]

Did you solve this issue ?
I have the exact same problem.

Thank you

[kekrystek]

I have the same problem. If I change from localhost in Cognos configuration to servername and restart the service it unregisters my service set at 9500, and registers service at 9300 and I get BI server not available.
Does anyone have a solution to this crazy loop I'm stuck in.