HPLaserJet4 will not print

Hello,
Our office recently bought new computers with Windows XP
Pro on them. Our HP LaserJet 4 Plus printer is having
problems printing. It will print fine for a while, then
it just stops. The print jobs are in the queue but they
will not print. I get no error messages. The only way
to get the printer to work again is to restart the
computer. We originally set it up with the driver
provided by Windows. I have also downloaded a driver
from the HP site and nothing is different. Occassionally
a print job will come through after an hour or so of
waiting. But usually we restart it before then. Any
help resolving this problem would be greatly appreciated.

Thanks so much...christie