Kali 1.1.0 64bit not booting from dvd.

I've downloaded kali-linux-1.1.0a-amd64.iso and followed the steps to verify the checksum but for some reason, my laptop refuses to boot from it. I have Ubuntu 14.10 and Win 7 dual booting on it at the moment and have specified the boot order in the bios to boot from the dvd first but it's having non of it.
I've also tried to run the setup from within Ubuntu but to no avail.
Is there something basic I'm not doing ?

Problem was that I had burnt a copy of the iso to the disk without having forst converted it to a cdr (using mac). All working ok now.