Actually, this seems to be the usage message from grub 0.99 - which is absolutely not supported on a SecureBoot-using system. You need to remove the 'grub' package and reinstall the 'grub-efi-amd64-signed' package that should have been installed when you installed the system.
** Changed in: shim-signed (Ubuntu) Status: Incomplete => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1198666 Title: package shim-signed 1.2+0~20120906.bcd0a4e8-0ubuntu4 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/shim-signed/+bug/1198666/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs