In BIOS you can tell your computer to boot an operating system located in a specific location. For example, if you have a live cd you can tell bios to boot from your DVD drive as appose to your hard drive. You may have an operating system stored on a flash drive, cd or several different hard drives in one machine. Your computers boot options will be automatically set to boot from the hard drive. When entering BIOS configuration zone you can choose the shortcut boot menu by observing your monitor at the earliest stages of powering on. The boot menu will tell your motherboard where to boot from. In advanced configuration mode, you can set your computers Boot Priority to always check the disk drive for a boot-able cd before you boot from your hard drive. This configuration is often used when an end user is experimenting with unfamiliar software. Try setting your BIOS options to satisfy your computing needs.