Tell us a little more. What exactly happens when you push the start button on the computer? Do you see the normal post messages, or whatever you usually see before the Mint menu appears? Does the menu appear? What exactly happens from then on?
Also, when you power up with the Mint live cd in the drive, what do you see? Go through the process as you did above.
Insanity: Doing the same thing over and over and each time expecting a different result.
Democracy is 2 wolves and a lamb voting on the menu. Liberty is an armed lamb protesting the electoral outcome. A Republic negates the need for an armed protest.