You need to go into the BIOS. If you're using a DVD and it's not seeing that early on after the BIOS boot, then the settings in the BIOS are wrong. You need to enter the BIOS and go into the section generally titled Boot Sequence and change the sequence from the hard drive from first in the sequence, and make the DVD drive the first in the boot up sequence. In this way after the BIOS boot you should see a screen that says "hit any key to boot from CD/DVD drive". You hit any key immediately and it will launch the disk in the DVD drive. Hope this helps!