On the phone with a Canon Tech for an hour and he concluded it was a Mac issue. Printer shows itself in system pref (printer) but will not communicate when trying to print. I have a Macbook Pro 10.5.8. I never had any problems until now. It was running wireless for over a year, but now I it won't even run via USB. Suggestions?

As I recall in Leopard there was/is an option in System Preferences > Print (&f ax?) to flush the print system. That will delete all your installed printers but the drivers are still there so reinstalling takes only a couple of minutes. That was always a sovereign cure for otherwise inexplicable print problems.

If that does not work or you are reluctant to try it there is a $30 utility called Print Therapy. Be sure and get the version that is appropriate for Leopard (OS X 10.5).

Mac OS X 10.5 Help: Resetting the printing system.

Note that among other things, this action "deletes all printer presets," so if you've got any unusual configurations saved as presets, you might want to make a note of them first.

One of the nice things about Print Therapy is that it gives you the option to preserve your presets.