I'm using Linux CentOS. I am unable to login in to root (su) when in a terminal. When I go and do any administrative tasks in linux 'windows' environment my root password works fine. For instance, I can change the root password vi a Applications->System Settings->Root Password. After that niether the old password nor the new password work in the terminal. The new root password is accepted for other root tasks that are not done inside the terminal, btw.