What is the Last Known Good Configuration and where does it come from?
Answer – Every time you boot successfully, Windows XP records your registry keys and device drivers. The Last Known Good Configuration option in the Windows Advanced Options Menu tells Windows XP to load up the last successful boot registry and device drivers
How do I boot Windows XP so that it uses the Last Known Good Configuration?
Answer – Follow the below procedure
Getting to the Last Known Good Configuration is easy. First, start your computer. As soon as the BIOS has finished loading, begin tapping the F8 key on your keyboard. Continue to do so until the Windows Advanced Options menu appears.
Once the Windows Advanced Options menu appears, select Last Known Good Configuration
If you begin tapping the F8 key too soon, some computers display a "keyboard error" message. To resolve this, restart the computer and try again
Other options (if Last Known Good Configuration does not work).
Try using System Restore To access System Restore, first boot into Safe Mode by tapping the F8 key on your keyboard. Continue to do so until the Windows Advanced Options menu appears. Then selecting Safe Mode
Once Safe Mode has loaded. Go to System Restore (Click Start, then All Programs, then Accessories, then System Tools, Then System Restore). Once in System Restore choose a restore point to Restore your computer.
If there are no restore points or the restore fails, then try to repair your boot sector
If that doesn’t work, as a last resort, do a Repair Install of XP.