I have keys setup on my Linux headless server and Putty on my Windows Desktop.
I can connect and authenticate successfully with Putty and authentication is via RSA Keys.
However, if I disable password authentication in sshd_config (PasswordAuthentication no) when I try and connection with Putty I get:
Server refused our key
And yet, if I then enable password authentication again, the key authentication works!
In addition, if I reset permissions of the /.ssh folder and authorized keys to 0700 and 0644, respectively.
I am able to disable password authentication and use the RSA Keys only until system reboot which then returns server refused our key again....