Pinguy OS on iMac

I am trying to install the OS on my iMac. I have burnt the iso to dvd and rebooted to the boot menu.

When the system tries to boot from the DVD all I get is a black screen with a flashing cursor at the top left. I have tried this with Ubuntu and Mint and get the same result.

My HDD has been partition using MS-DOS format, is this correct?

Any help would be greatly appreciated