UEFI. Thank you for making the very first step in using a new computer more difficult. As if there wasn't already enough trouble for this less than really intelligent PC user.
When/if your ready I can walk you though. But for you it should be a lot easier, as you've not messed with Beta. Wait a month or two and Mint will have all this cleaned up and ready to dance.":O}
Why thank you! I'm happy to wait for the easy to install release. Then again, if it ain't broke, don't fix it. Mint Cinnamon 17.1 forever?