Hello,
Not so long ago, I had a similar issue but for some reason I just can't find the reference to fix this. When I'm inside my admin panel suddenly, when I click on something I saw the login screen again and my username & password doesn't work.
I fixed this previously but I can't find the reference in the forums and/or by email.
Thanks for pointing me to the right direction, will keep a note regarding this issue if it happens again.
Jesus