If your Print Services for Macintosh occassionally fails to work, your Macintosh clients may be sending a Postscript level-two print job to a PCL (Printer Control Language) print queue.
You may also receive Event ID 2019 or Event ID 4011.
PCL print queues only accept PostScript level-one or PCL print jobs from Macintosh clients.
Postscript level-two print jobs can be sent to a Postscript print queue because Windows NT just passes it through to the printer, without altering it.
NOTE: Print Services for Macintosh uses True Image to convert PostScript level-one to PCL for a PCL print queue.