What is the purpose for Last Known Good Configuration function and how to enable it?

What is the Last Known Good Configuration function?

This function allows users to restart the computer using the last settings in which the computer works properly. All registry's information and the settings of drivers that are working properly during the last configuration are restored. Use this function only if the operating system does not restart properly after making changes or installing new drivers or devices.

Follow the steps below to enable the function:
1. At the Sony logo, press and hold F8 for a second.
2. Select Windows® advanced Options Menu and press Enter.
3. Select Last Known Good Configuration and press Enter.
4. Select Microsoft Windows® 2000 Professional and press Enter.
5. If the computer contains multiple hardware profile, select one profile and press Enter.