I tried it with the core2duo image as well and it booted fine and brought me to the login prompt. From my cursory investigation it seems this error message occurs when there is corruption with the grub boot record. Can you do the following to ensure that the image you have is identical/whole?
$ cksum faceswap-server-release-core2duo.qcow
735455956 8208121856 faceswap-server-release-core2duo.qcow
If you don't get the same checksum, then it is possible there was a problem with the download from our storage cluster.