The problem seems to be with the laptop's BIOS.
Error 18: Selected cylinder exceeds maximum support by BIOS

At the boot Grub screen:

geometry (hd0) -> lists partitions 0-6
find /boot/grub/menu/lst -> (hd0,5)


If I boot Linux and run Grub:

geometry (hd0) -> lists partitions 0-8
find /boot/grub/menu/lst -> (hd0,5) (hd0,8)

If I can't work around this limitation of the BIOS, I may need to reorder some of my partitions.