Do you have another account without a . (dot) in it that you can test and try to login with?
Are you using Hive Auth, Hive Keychain, or manually typing in your posting key?
If possible, open Incognito, and try to login that way.
There are a few more things to try ..
Posted via D.Buzz
Until I began having my problem, I had been using Hivesigner and typing the Hivesigner password. After I began having this problem, I've been using PeakD to login by copying and pasting the Posting Key.
Using an Incognito window, I attempted login as both
magnacarta.buzz
andmagnacarta
and each time manually entering the relevant Posting Key. For both account names, Authorization failed.