Strange Network printer problem

Hi,

we have two printers in our network, both connected to a different computer.
When installed, they worked well, but now and then they refuse to print and
they show a strange bahaviour.

When looking in the Queue (Spooler), the print jobs are cycling.
So, the first becomes the last while the second becomes the first, thirt
becomes second, etc

When we restart the computer, the printer starts printing, just befor
shutdown.
We Run XP-pro.

it is an old panasonic matrix printer (used for labels) and a HP officejet
HP 1170c, both connected to a parallel port.

Any ideas?????

Thanks,
Ben