Forum user has confusing login
 

I have a registered user who, when she logs in, she gets the page which says "you are not authorized to view this page."

When she clicks on the "Forum" tab she is fully logged in and has full proper access to the forum.

I have asked her to delete all her cookies, history, form data and passwords, but the result is the same even after rebooting the system.

I am stumped. What else can I suggest to her?