Problem resolved. Below is a copy of the message sent to my client.

The problem of CIS correspondence inconsistently dropping pages and data was identified. There was a change made to the print server where the driver assignment for the selected printer, the Infoprint 40, was being made at the server level rather than the workstation level. Although the workstation identified the HP5 driver for the Infoprint 40 printer, the print server overrode this assignment and used the Infoprint 40 driver when sending the CIS correspondence to the printer. We has always experienced inconsistent results when using the Infoprint 40 driver for CIS correspondence but have used the HP5 driver with success.

The server level assignment was removed for the Infoprint 40.

Daniel