Know about system "Last of the Known Good Configuration"

Every single time you manage to load Windows XP successfully, Windows saves certain registry keys and applications settings on your PC. This way if you ever boot your computer and for some reason Windows fails to properly load, you can use the Last Known Good Configuration to boot Windows to the last known good settings

To put this configuration to use as your booting Windows, press the F8 key as Windows starts, and then select the Last Known Good configuration option. Your PC will then take the action of loading Windows using these previously saved settings.