If you are connected via USB and receive this message, make sure the Wireless button on the back of the scanner is set to "OFF". By default, it is set to "ON" and you will receive this error message if trying to use the scanner via USB.
While attempting to scan you receive the error message "Driver not found" or a TWAIN error . Do you know if a Windows update was applied recently? If so, it is possible that the .INI
