@sarahr:
If you are using a machine with EFI instead of standard BIOS your problem is that there is not a normal MBR on a GPT formatted drive. A BIOS boot partition must be created in order for Grub to be correctly installed. I ran into the same problem when I was setting up the dual boot on my new laptop with Windows 8. At first I tried to set up a partition for Mint and ran into the same problem with Grub not installing correctly. I solved it by selecting to install side by side with Windows. The installer then on it's own created the BIOS boot partition and installed Grub and all was well.
There may be other effective methods. I'm just saying that this is what ended up working for me.







