When installing grub to the MBR, the bootable flag is irrelevant. That only matters if you are using a DOS MBR.
It might be a little late now since you were able to successfully install by choosing where to install the booloader on a subsequent installer, but would you mind elaborating on the exact configuration of your drives from the failed install?
IDE port 0: drive I'm not doing anything with
Sata port 0: nothing connected
Sata port 1: drive I installed to
What order did you have them configured to boot from the BIOS as well?