Why can I no longer print from my Windows XP computers to my Bonjour connected Canon printer thru an Airport Extreme Base Station (f/w 7.6.4, model A1301)?

Something has changed recently and I haven't figured it out. My 2 Windows XP computers are no longer able to print via Bonjour. I have tried removing and reinstalling Bonjour. Upgrading the firmware on the AIrport Extreme Base Station and comparing Port settings from an able to print Windows Vista laptop. Port settings match and Bonjour says it sees the printer...but the communication is not happening between the computer and the networked printer, it times out and produces an error in the print que. Both XP computers have no problem using the internet via the Base Station. One is wired and one is wireless. Thoughts?