ssh/sshd connects but does nothing, putty/sshd works fine

[Randy Orrison <randy@orrison.com>]

I'm trying to solve a puzzling problem.  I can use putty on my WindowsXP 
notebook at work to connect to my home debian box, or to my debian box 
at work, and it works fine.  When I try to connect from my debian box at 
work to the box at home, it connects (according to the logs on both 
sides) but doesn't give me a prompt, and eventually times out.  Details:

debian box at work:
  debian 3.0
  kernel: 2.4.18-1-686
  ssh -V: OpenSSH_3.8.1p1 Debian 1:3.8.1p1-6.backports.org.1,
              OpenSSL 0.9.6c 21 dec 2001

debian box at home:
  debian 3.1
  kernel: 2.6.10-1-k7
  ssh -V: OpenSSH_3.8.1p1 Debian-8.sarge.4,
              OpenSSL 0.9.7e 25 Oct 2004

When I connect from putty, auth.log at home shows:

Feb 21 16:59:53 evo sshd[16697]:
        Connection from 80.46.104.22 port 59507
Feb 21 16:59:54 evo sshd[16697]:
        reverse mapping checking getaddrinfo for
        dsl-80-46-104-22.access.uk.tiscali.com failed
        - POSSIBLE BREAKIN ATTEMPT!
Feb 21 16:59:54 evo sshd[16697]:
        Failed none for randy from 80.46.104.22 port 59507 ssh2
Feb 21 16:59:54 evo sshd[16697]:
        Found matching RSA key: (snip)
Feb 21 16:59:55 evo sshd[16697]:
        Found matching RSA key: (snip)
Feb 21 16:59:55 evo sshd[16697]:
        Accepted publickey for randy from 80.46.104.22 port 59507 ssh2
Feb 21 16:59:55 evo sshd[16699]:
        (pam_unix) session opened for user randy by (uid=0)

When I connect from the debian box at work, auth.log at home shows 
exactly the same sequence of messages, except with different RSA keys.

Here's the last few lines of ssh -v output from the box at work when I 
try to connect:

debian.box.at.work$ ssh -v -v debian.box.at.home
[.. snip many lines ..]
debug1: Trying private key: /home/randy/.ssh/identity
debug1: Offering public key: /home/randy/.ssh/id_rsa
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: pkalg ssh-rsa blen 149
debug2: input_userauth_pk_ok: fp (snip)
debug1: read PEM private key done: type RSA
debug1: Authentication succeeded (publickey).
debug1: channel 0: new [client-session]
debug2: channel 0: send open
debug1: Entering interactive session.
debug2: callback start
debug2: ssh_session2_setup: id 0
debug2: channel 0: request pty-req
debug2: channel 0: request shell
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
[.. sit and wait for timeout error ..]

So everything that I can see looks like it's working fine from both 
ends, but it doesn't work.

What else should I be looking at?  (I've just upgraded to the backport 
of 3.8 in hopes that would help, but it didn't.  Same thing with the 
previous version.)

Thank you,

Randy Orrison