I have just clicked on sign out button in 2013 ECP and can no longer log in again, I can log in to OWA
This is a new installation and yes I made a full backup before I started to configure it, so I can go back to that if need be but unless I know why it will probably happen again.
I am using Exchange 2013 CU6 installed on 2012 standard.
I have just figured out that if I clear Internet Explorer cache, I can login again, so it looks as if it is an IE10 fault rather than Exchange