Try typing F8 at startup and in the list of Boot selections, select Mode safe using ARROW top to go there > and then press ENTER. Go to your Bios/Setup, or the Boot Menu at startup and change the Boot order to make the DVD/CD drive 1st in the boot order, then reboot with the disk in the drive. At the startup/power on you should see at the bottom of the screen either F2 or DELETE, go to Setup/Bios or F12 for the Boot Menu