I just fixed this problem.
I re-downloaded the printer drivers from Canon, looked for them in the "downloads" directory on my computer, DISCONNECTED the printer from the computer, ran the downloaded .exe file and ran the printer driver installation wizard (automatic, just click yes and OK where prompted), This replaced the old drivers. Then reconnected the printer to the computer and turned it on, the computer found the printer and it went through 10 minutes of self induced gyrations, and was fixed.
Previously I tried:
taking printer head out and putting it back in;
looking for dirt or spilled ink on printer head (there was none);
hard reset (turn off, press stop button 2 seconds, press on button while holding stop button, let go of stop button, hold start button down still, press the stop button 4 times, or 5, let go of start button).
Replaced ink cartridges with Canon official ones.
None of that worked. Error just reappeared each time.
It was squirreled up or out of date printer drivers!!!! Occurred for absolutely no discernable reason to a previously perfectly working printer/scanner. Glad I was able to save it with this super simple fix because I like it and it was expensive and right now I NEED it to work. I just tried the redownload drivers thing as a last ditch guess.
