putty: Access Denied

IP/host name, username and password are correct but you get Access Denied when tyring to log in.
Try disabling this setting:

Putty has GSSAPI enabled by default.

Turn it off if you are not using Kerberos (and chances are, you are not in your environment).
Explanation:
I dealt with a few weeks back with when a new administrator could not login to any ssh host with putty - even the one that I know should be working for him. It seems that with GSSAPI Auth enabled, Putty will attempt to login with non-existent kerberos credentials, which resulted in an immediate Access Denied message.
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Source: http://serverfault.com/questions/317781/putty-access-denied