One of the machines on my network (Mint 12 workstation, up to date) periodically gets into a bad state wherein all outgoing SSH connections fall back to password authentication with the error "agent admitted failure to sign using the key" instead of using the key-based authentication which has been configured.
Once it's in this state it will fail 100% of the time for all outgoing connections. Incoming key-based authentication appears to connect normally. I have tried deleting and regenerating the keypair and redistributing the public key, but the error persists.
A reboot will temporarily resolve the error, but it comes back again in a few days. Doesn't seem to coincide with any particular event/workflow, but I might be missing something.
Has anyone else seen this?