I love google...yes, the fix is CORRECTLY described on page 1.
A). Click ADD PRINTER....Next select WHICH PORT its on...this is the "trick"!...select the VIRTUAL USB PORT....hit NEXT (if you are trying standard "printer port 1" that is your problem, must be virtual usb port.
B), go thru and have Windows update its list of drivers
, takes several minutes, don't bother going through Canon its not necessary. Once you see MP780 (or etc) listed, select it, all works from there.
I had tried from Canon...but the trouble-shooter during Canon's driver
install process correctly identified that the port couldn't listen for the printer...just wasn't sure why the correct port wasn't in use or how to change it...but now its all working fine (test page printed etc).