Shared Printer issues

I posted this on the print_fax forum but have gotten no replies so I will
try here.

Have two systems doing the same thing. Dell Optiplex computers running XP
Professional SP2 with all the latest patches. HP 1018 printer connected via
USB and shared. Printer will work for a while and then stop printing. If
you stop and restart the spooler the print jobs start again. There is
nothing of interest in the Event Viewer when this happens.

Any ideas are appreciated.