Description of problem:
When installing F7 using diskboot.img on a USB key, GRUB is installed on the USB
key and not on the harddrive as expected.
Meaning, that after the installation of F7 is complete it can't boot without the
USB key is inserted.
This basically means that your BIOS is telling us that the first BIOS drive is
the USB key when you're doing the install and so we default to using it. You
can change the drive the boot loader is installed to either from the
partitioning or the advanced bootloader screen.
Unfortunately, there's not much we can do to better auto-detect things :(
But it worked in Fedora 6...