Print jobs not spooling (apparently)--but spooler is on

When I attempt to print PDFs of more than, say, 50 pages, print spooling does
not appear to work. The problem does not occur on large Word documents. I
have Windows XP SP2. I have a Linksys 2-port printer server. The printer is
an HP Laserjet 5.

I have checked Printers and Faxes on all of my machines (3) and Print
Spooling is ON. The sam eproblem occurs on all of the machines.

The symptom is that when I print large PDFs (more than 50 pages or so), XP
sends the first 45 pages or so to the printer right away, as shown by the
progress bar, but then stops sending the rest of the pages. The printer then
starts printing all of the pages but after the 50 pages or so, it starts
printing them very slowly. I mean very slowly. The printer says
"Processing...." as if it is receiving bits from the computer about one every
5 seconds. However, the complete document eventually prints. However, it
takes a long time.

The problem is that until the document is printed, the machine is
inaccessible for other tasks. THe hour glass is running.

What is the problem? How can I fix it?

Thanks.