SP2 and Print Servers

I have a small network of XP Home PC's that printed to a
print server connected to a large format printer. The
printer has no available Windows driver but, projects are
printed directly through the design software. The server
recieved data via IP address.

Upon installing SP2, I get the "cannot open port" error.
I have checked the IP address and Firewall to be sure
things are in order there. The print server wizard is
able to recognize the server and the printer, still no
change. I have tried setting different addresses, ports,
cables, and even a different print server with no change.

I can get the data to the printer via direct cable but,
that is only a short term fix, we need the print server
back.

Please help if you have any ideas!