OpenSSH 2.5.2p2, Linux, and not accepting passwords

[Roy S. Rapoport]

Well this is bizarre.

Default install of openssh on this linux box (originally RedHat
but I think someone's put a new kernel on it -- it reports itself
as 2.2.12-20 when I do uname -a.  Sorry, Solaris is my forte, not
Linux).

It all works.

Oh, except for logging in using password authentication.  It
prompts for a password, but reports incorrect password.  And,
umm, I'm pretty darn sure I type it correctly.  That's not an issue.

How the heck do I debug this?

-roy