can't print from wireless laptop to shared printer

Hey All,

If I add a printer from my xp laptop I can print to the shared lexmark
printer on my vista desktop over my wireless network. If I reboot the
laptop and try to print, I get an error message saying that I don't
have permission to access the printer. If I reboot the laptop I have
to delete the printer an add it again to print. And when I add the
printer the second time it asks for a username and password before it
will add the printer. Any ideas on how to configure the laptop/desktop
so that I can print after a reboot without deleting and adding the
printer?

Thanks In Advance,

David