When you boot the CD/DVD of Mint you should see a screen with a 10 second countdown?
During the 10 second count down during boot press a key.
Then press the Tab key to edit the boot parameters, and on the line of text that appeared near the bottom append the word "nomodeset
" (without the quotes).
Find the line ending with "quiet splash".
Add your boot option just in front of these key words -
i.e. so the line looks like ..."nomodeset
quiet splash". No "'s needed remember.
It will look something like this: http://i.stack.imgur.com/BnUQa.png