Black screen with blinking cursor!

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http://askubuntu.com – I downloaded the live image file for Ubuntu 12.04 LTS. I then went into Bios and set installation settings to (first) CD drive and (second) disabled. When i boot i only get a black screen with a blinking cursor after some time i might get some error messages. Leave it for hours but nothing else. FYI:I dont know how to goto grub menu. Im a noob. By the way im 13 so make the answers easy RSVP (HowTos)