ppp fails only to work site

[Ralph Winslow <rjw@nac.net>]

For the last couple of weeks I've been unable to connect to work via
ppp.
When I run minicom, I see the host: prompt and enter ppp, then get the
password:
prompt and enter my password, then see the ppp garbage strings that
start the 
protocol negotiation.  I believe that this confirms that the password is
OK.
When I tail -f /var/log/messages in another window, I see:

Jan  5 00:20:26 localhost chat[19028]: host:
Jan  5 00:20:26 localhost chat[19028]:  -- got it 
Jan  5 00:20:26 localhost chat[19028]: send (??????)
Jan  5 00:20:28 localhost chat[19028]: expect (ssword:)
Jan  5 00:20:28 localhost chat[19028]:  ppp^M
Jan  5 00:20:28 localhost chat[19028]: Password:
Jan  5 00:20:28 localhost chat[19028]:  -- got it 
Jan  5 00:20:28 localhost chat[19028]: send (??????)
Jan  5 00:20:28 localhost chat[19028]: send (\d)
Jan  5 00:20:29 localhost pppd[19027]: Serial connection established.
Jan  5 00:20:29 localhost pppd[19027]: Using interface ppp0
Jan  5 00:20:29 localhost pppd[19027]: Connect: ppp0 <--> /dev/ttyS1
Jan  5 00:20:33 localhost pppd[19027]: Remote message: Invalid Login
Jan  5 00:20:33 localhost pppd[19027]: PAP authentication failed

Can anyone help with how to proceed?  TIA
-- 
-----------------------------------------
Ralph Winslow		      rjw@nac.net
The IQ of the group is that of the member
whose IQ is lowest  divided by the number
of members.