Hi,
Canon Scan N650U/N656U is not compatible with windows 7 follow the link below to check compatibility for Canon Scan N650U/N656U:
I would suggest you to install Canon Scan N650U/N656U driver in compatibility mode. Follow the steps below to install driver for Canon Scan N650U/N656U:
Step 1:
Download Canon Scan N650U/N656U driver from the links and choose Windows XP to download:
Step 2:
After above step install Canon Scan N650U/N656Udriver in Windows vista compatibility mode, follow these steps:
a. Right-click the Canon Scan N650U driver file, and then click Properties.
b. In the Package Name Properties dialog box, click the Compatibility tab.
c. Click to select the Run this program in compatibility mode for check box, click Windows XP (Service Pack 2) in the Run this program in compatibility mode for list, and then click OK.
d. Double-click the executable file to start the installation program.
For more information have a look at the following link:
http://windows.microsoft.com/en-US/windows-vista/Make-older-programs-run-in-this-version-of-Windows