The Last Known Good Configuration is a start up option that allows you to start the computer with settings that worked. This option can be a real life saver after you've installed a wayward application that prevents your computer from starting up normally. The Last Known Good Configuration also allows you to return to a working set of drivers after you install a driver that whacked out your system. To get the Last Known Good Configuration going, just do the following:

1. Reboot the computer. You'll usually see a BIOS screen that shows the manufacturer of the BIOS or you'll see a pretty-full screen ad for the maker of your computer.
2. If you have multiple operating systems installed on the computer, you'll get a boot menu. At the boot menu, select the operating system of interest, and press the F8 key on the keyboard. If you don't have a boot menu, you want to make sure that you press F8 after the BIOS screen but before the graphical "Starting Windows XP" screen comes up. Try pressing F8 again and again after the BIOS screen shows up and stop when you see the Advanced Options Menu.
3. In the Advanced Options Menu, select the Last Known Good Configuration (your most recent settings that worked) option. Then press [ENTER].
4. After pressing [ENTER] you'll see a list of operating systems on the computer. If you have only one, you're set! Just press [ENTER]. If you have more than one, select the one you want to boot into and press [ENTER].
5. The computer starts up with a configuration that worked!

We highly recommend you use this option when you find yourself in a jam with Windows XP.