to give some more info, specially on the problem computer. Start with the setup on the XP machine that works and then on the one that does not. What is different?
I just unplugged an HP1300 laserjet and plugged in a new HP P2055dn laserjet. The HP 1300 worked fine before on all Apple and Windows machines. The new printer now works on all machines except (!) the XP machine. Nothing was changed (except switching printers), and except installing the new driver.
Here is the configuration: The printer has a USB connection to an Apple Airport Express wireless router. The XP PC communicates via this router.
Any ideas. I am going crazy -- HP is no help at all.