I would be surprised that the v2.3 update has done this. None of my Canon inkjets are showing the same symptom after running the update, although I don't have any machine as old as your i860. Personally I think that your print head could be the cause and the update timing is a coincidence. With a faulty print head, you would get no output even then though your supply levels still show the black ink as full.
I suggest you try a nozzle test. If you open Print & Fax, select the i860 and then click Options & Supplies, you should see a Utility tab. Select this and click Open Printer Utility. Then select the i860 and press the Maintenance button. Change the menu to Test Print and then select Nozzle Check. This will print a page and show you if all the inks are working. I would expect the black not to appear on this printed sheet. If this is so, you can then change the menu to Cleaning and click the Cleaning button. Do another nozzle test. If the black still does not print, then try doing Deep Cleaning.
