I've had an abrubt problem with my scanner on my Pixma 780 & I've uninstalled & tried re-installing my original software. My problem now seems that I'm totally unable to even get the printer to print. I Uninstalled the software & followed the procedures by the manual & yes was able to print , but couldn't use my scanner. I would constantly receive the error "Twain device was not ready or user cancelled" . Now I can't even use it to print. Yes, I did install all software with USB cable disconnected before trying to use. I've even gone as far as deleting all "Canon" registry settings except for secondary camera software & starting all over without any luck. I'm using XP SP2 with 1 gig of ram. Please ask for any other pertinent info that would help to remedy this nusance for me. Many thanks all.................Gary.