Hint: WordPress Login Problems? If you see the message “You do not have sufficient permissions to access this page” while you’re totally sure Username and Password were correct, check your browsers settings wether or not “Referer” are activated.
WordPress is a little bit Anti-Privacy and needs you to have the Referer activated to use the Backend.
Needless to say that it’s totally unsafe to rely on that header … . I wonder how that turns out to work or not behind those gateways that are filtering certain headers. Hmm.