Just bought a Canon MP 780 multifunction (as recommended by PC Pro!!!). Got the test sheet and one colour print - since then I can't get past a paper jam error message. I've checked all the obvious, accessible parts but am pretty sure there is no paper jammed anywhere! Also carriage does not go back to the middle when I open the door. I've had similar problems with an HP3820 which I've since been told was a design fault! Any solutions anyone???