Apparently the drivers for that printer are embedded in Win7.
I assume that you have Win7 64 bit?
There is, however, an add-on that you can try. This may correct the scanning problem and appears to be 32 and 64 bit compatible.
(you may need the serial number off the printer)
http://software.canon-europe.com/software/0035869.asp?model=
EDIT:
RandyL found the 64bit drivers.
http://software.canon-europe.com/software/0035913.asp?model
Try these first then, if you still have the same problem, try the add-on link.