A new firmware has been posted to the Canon USA website that addresses this issue. This fix resolves a problem that, in rare cases, causes a memory full message to be displayed, and subsequent sending to be prevented, when sending a fax. Please click the link below to view more information and instructions on downloading and installing the firmware:
I hope that this information is helpful to you. Should you experience any issues or need further assistance, please contact us at 1-800-OK-CANON (1-800-652-2666). Have a good day.