It sounds like you've got an EFI-based computer, but it's conceivable the installer got confused and tried to install the wrong package. To be sure, check your Windows boot mode, as described here.
If you're booting Windows in EFI mode, you should almost certainly try to boot Linux in EFI mode, too. Several EFI boot managers and boot loaders exist; see this page I've written
for details. Unfortunately, the GRUB 2 that Mint uses by default is easily the worst of these boot loaders, in my experience -- it's finicky and gets things wrong far too often. So you've got two main options, but the second has several variants. You might luck out with any of them and get it working quickly, or you might struggle with any of them:
- You can try to fix GRUB 2 as delivered by Mint. To do this, you'll need to look for the files it's installed in /boot/grub and /boot/efi/EFI/linuxmint (or conceivably some other subdirectory of /boot/efi/EFI), examine your EFI's boot loader list with the "efibootmgr" utility, examine the grub.cfg file (probably stored in /boot/grub), and troubleshoot in general.
- You can install another boot loader to replace GRUB 2. This may be easier to start with, but since Linux Mint assumes the use of GRUB 2, you'll have more in the way of ongoing maintenance. My recommendation is to use either Fedora's patched GRUB Legacy (binary links are available here) or a combination of ELILO (a Mint package exists, called "elilo") to boot Linux and either rEFIt (a Mint package exists, called "refit") or rEFInd (there's no Mint package, but it's an updated and improved fork of rEFIt) to select the OS. Eventually, a combination of rEFInd with a 3.3.0 or later kernel will be the easiest to install and maintain, but Mint doesn't yet ship with a new enough kernel for this to work.
Post back with confirmation (or denial) that you're booting Windows in EFI mode and a decision on what general approach you'd like to take and I (and perhaps others) can help you with the details.