When one (and only one) user tries to access Exchange admin center (https://mail.domain.com/ecp), they get the following:
error
Sorry, your request couldn't be completed. Try deleting the cookies from your browser, and then sign in again. If the problem continues, contact your helpdesk.
Well, they are the helpdesk. It doesn't matter the browser or the computer she tries to access it from, it always appears. She has deleted the cookies, etc. without resolution. She can, however, access https://mail.domain.com/owa without any problems.
Thanks,
Don - Intellys