I have the ip4000
I downloaded the Windows 7 drivers
from Canon and installed them before I first plugged the printer in.
As soon as I plugged it in it searched for the Canon drivers, found them, and all is working OK.
Same thing with my Lide 60 scanner.
I think you must install the drivers before plugging in the device otherwise you will need to remove the device (device manager) and get it to rescan for drivers.