Shot in the dark here....
1. Check that the latest and greatest versions of the Win2000 driver for that printer oare loaded on the clients (obvious I know, but I have to say it). Also make sure to check any settings in the driver on the client which refer to direct communication to the printer (as some try to communicate directly with the printer via Bi-Directional communication)
2. Check the BIOS of the server and see what communication mode the parallel port is set too (usually variants of EPP, ECP).
I will bet a buck on the BIOS setting
