An error occurred while receiving the fax

Subject message is consistently, and persistently received
on 'most any occasion when we try to receive a fax.

Since XP Pro has been installed, I think the PC has
received ONE fax, sent from the fax machine on an
alternate line, sitting next to the PC. NEVER has another
machine sent a fax that was successfully received.

How can I diagnose this failure? How can I ascertain what
is failing where? Even the phone company says all's well
on the line. Even though we do NOT receive anything more
than subject message.

As an example, the Fax Monitor currently shows:
17:17:0 Ringing
17:17:5 Ringing
17:17:8 The call was answered
17:18:1 An error occurred while receiving the fax

The last line has a white X in a solid red circle to the
left of the time stamp.

In view of the highly revealing nature of the message, I
am at a complete loss as to where to go, or what to do, to
persuade this PC to receive a fax with this software.