After printing a few documents ok, my printer always stalls (for want of a better description) and only restarts when I reboot the pc. When it stalls, I can see the print jobs in the queue, with the first one in status "printing". There is no indication that anything is wrong. I'm on Win XP, the printer is a Xerox XK50 attached via USB. I've reloaded the print driver and firmware, but makes no difference.