Okay, here's a strange one.

We have a Canon printer that's on the WiFi network. My Mac is multi-homed on Ethernet and WiFi, but I have Ethernet prioritized so I don't chew wireless bandwidth when I'm within cable distance of the router.

When I go to PRINT something, though, the Mac simply can't manage to communicate with the printer. If I prioritize WiFi over Ethernet, though, it works the way it should.

Any ideas?