Hi pigwheelin.
I will be glad to assist you.
Since you are able to scan using the Windows Fax & Scan program, then there may be a conflict with the TWAIN driver.
Please follow the steps below to check for conflict:
1. Open the [File Explorer] window and click [Computer].
2. Double-click the [C://] drive.
3. Double-click the [Windows] folder.
4. Double-click the [TWAIN_32] folder.
5. Drag all items, except for the MF4500 Series and WIA.DS file, to your desktop.
6. Close the folder.
7. Restart the computer.
After the computer is back on, please try scanning again. If the error persists, please call us at 1-800-OK-CANON (1-800-652-2666), Monday - Friday, 10:00 AM - 6:30 PM EST.