How to Restore the Last Known Good Configuration
Last Known Good Configuration is usually used to enable the operating system to start if it fails after the Starting Windows logo is displayed. Using Last Known Good Configuration helps to correct instability or startup problems by reversing the most recent system, driver, and registry changes within a hardware profile. When you use this feature, you lose all configuration changes that were made since you last successfully started your computer.
Using the Last Known Good Configuration restores previous drivers and also restores registry settings for the subkey HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet. Windows Vista does not update the LastKnownGood control set until you successfully start the operating system in normal mode and log on.
When you are troubleshooting, it is recommended that you use Last Known Good Configuration before you try other startup options, such as safe mode. However, if you decide to use safe mode first, logging on to the computer in safe mode does not update the LastKnownGood control set. Therefore, Last Known Good Configuration remains an option if you cannot resolve your problem by using safe mode.
To access the Last Known Good Configuration startup option, follow these steps:
- Remove all floppy disks, CDs, DVDs, and other bootable media from your computer and then restart your computer.
- Press F8 at the operating system menu. If the operating system menu does not appear, press F8 repeatedly after the firmware POST process completes but before the Starting Windows logo appears. The Advanced Boot Options menu appears.
- On the Advanced Boot Options menu, select Last Known Good Configuration (Advanced).
Use Last Known Good Configuration to restore some settings to their state during the last time a user successfully logged on.
When Windows starts, it reads status information from the file %WinDir%\Bootstat.dat. If Windows detects that the last startup attempt was unsuccessful, it automatically displays the startup recovery menu, which provides startup options similar to the Advanced Boot Options menu, without requiring you to press F8.
Note If you suspect that changes made since you last successfully restarted the computer are causing problems, do not start Windows and log on normally-logging on overwrites the LastKnownGood control set. Instead, restart the computer and use the Last Known Good Configuration. You can also log on in safe mode without overwriting the Last Known Good Configuration. For more information about control sets, see the section titled "Kernel Loading Phase" earlier in this tutorial.
How to Use System Restore
If Last Known Good Configuration fails to resolve the problem, you can manually perform a system restore if Startup Repair did not initiate it. However, Startup Repair would typically have taken this step already if it might have solved the problem. For information on how to use System Restore, see the section titled "How to Use System Restore" earlier in this tutorial.
In this tutorial:
- Configuring Startup and Troubleshooting Startup Issues
- What is New with Windows Startup
- Boot Configuration Data
- BCD Stores
- System Recovery
- Windows Boot Performance Diagnostics
- Understanding the Startup Process
- Power-on Self Test Phase
- Initial Startup Phase
- Initial Startup Phase for BIOS Computers
- Initial Startup Phase for EFI Computers
- Windows Boot Manager Phase
- Windows Boot Loader Phase
- Kernel Loading Phase
- Control Sets
- Values for the Start Registry Entry
- Value Descriptions for Type Entries
- Other Registry Entries in the Servicename Subkeys
- Session Manager
- Logon Phase
- Important Startup Files
- How to Configure Startup Settings
- How to Use the Startup And Recovery Dialog Box
- How to Use the System Configuration Tool
- How to Use BCDEdit
- How to Interpret BCDEdit Output
- How to Back Up and Restore Settings
- How to Change the Default Operating System Entry
- How to Change the Boot Menu Time-Out
- How to Change the Order of Boot Manager Menu Items
- How to Create an Entry for Another Operating System
- How to Remove a Boot Entry
- How to View and Update Global Debugger Settings
- How to Remove the Windows 7 Boot Loader
- How to Configure a User Account to Automatically Log On
- How to Disable the Windows Startup Sound
- How to Speed Up the Startup Process
- The Process of Troubleshooting Startup
- Startup Troubleshooting Before the Starting Windows Logo Appears
- How to Start the System Recovery Tools
- How to Run Startup Repair
- How to Use BootRec.exe
- How to Diagnose Hardware Problems
- How to Use System Restore
- How to Manually Repair the Boot Sector
- How to Manually Update the BCD Registry File
- How to Manually Replace Files
- How to Reinstall Windows
- Startup Troubleshooting After the Starting Windows Logo Appears
- How to Restore the Last Known Good Configuration
- How to Enable Boot Logging
- How to Start in Safe Mode
- How to Identify Failing Drivers and Services
- How to Analyze Startup Problems in Safe Mode
- Event Viewer (Eventvwr.msc)
- System Information
- Error Reporting Service
- How to Use Device Manager to View or Change Resources
- How to Analyze Boot Logs
- How to Roll Back Drivers
- How to Temporarily Disable a Service
- Troubleshooting Startup Problems After Logon
- How to Temporarily Disable Startup Applications and Processes
- How to Disable Startup Applications Using the Shift Key
- How to Disable Startup Programs Using the System Configuration Utility
- How to Disable Startup Applications Configured Using Group Policy or Logon Scripts
- How to Permanently Disable Startup Applications and Processes
- Manually Remove the Entry