There appears to be a problem with version 15's drill file output that I didn't have in the previous verison. Sunstone Circuits rejected the drill file for a PCB that I had updated using the new version. All previous revisions of the PCB were okay (those done using older versions of EasyPC).
The new drill file contains not only the drill information but also lines and shapes that have to do with a copper pour. When I "clear copper" the drill file is okay.