Passwords don't work anywhere, SSH pubkey does. PAM problem?

[Joshua Gardner]

I cannot use passwords at all anymore, anywhere in the system. I first
noticed this when I could no longer log in with IMAP to my mail server
(Citadel, not that that really matters). I then logged in to my home
server box with SSH, which I use public key authentication for, which
strangely worked. I tried to restart my mail server, as I'd once
before had a problem with not being able to log into it that
restarting fixed. The trouble is that sudo didn't work. Sudo prompted
me for my password, which I supplied, and then it just exited. If I
enter an incorrect password, it gives me an error message and
reprompts, so it's not that my password has changed or that it can't
read it.

Sudo isn't the only thing with this problem either. Getty (the console
login manager) doesn't work either. It gives the same behavior: error
message informing of bad password if the password is incorrect,
exiting on correct.

Nothing that uses PAM for auth seems to work. My mail server, getty,
sudo. I didn't do anything to PAM to cause this, so I don't know where
to begin to fix it. I can't get root normally but I can boot into
recovery mode. Any pointers toward anything that can help is much
appreciated.

--Josh
-- 
We may come to Jesus and ask Him; He will know all about it; if He comes to a
little child, he will adapt himself to the language and capacity of a little
child.
		-- Joseph Smith, Jr.