Hi BorealHobbit.
Thank you for using the forum.
I searched the product knowledge base but was not able to identify a solution for the exact issue you have described. I would suggest contacting support at 1-800-821-2797.
I am not technical but might suggest reloading the software or even power the printer off and on.
http://www.support.xerox.com/support/WC780X/support/en_US.html?objGUID=16062
CAUTIONS:
after putting the phone number in, we push the Start button, which is supposed to start the scanning of the document (which is waiting in the document feeder) the display says "Building..." and nothing else happens. Any help would be appreciated.