problems with Netware print queues

In windows XP I am having trouble with Netware printers.
I setup the printer in windows and printing works fine for
about an hour and a half then suddenly I get an error that
the printer cannot be found. I have to delete the printer
from the registry and reboot the computer. I then re-add
the printer and the process starts all over again. Anyone
have any idea about why this is?