I've marked this for the PM to review.
Thanks for the feedback.
Please make sure that the EOC and Orion servers are in the Trusted Sites of your browser. Hope that helps.
You can also check whether you are using local site url (without "." in the name), when not, you should add it explicitly into Internet Explorer - Internet Options - Security - Local Intranet sites.
Its also possible to check whether your users can login automatically to Orion (without entering EOC first) from Internet Explorer by typing Orion Url directly.