I’m sure many of you have seen the Last Known Good Configuration option at some point or another when starting Windows, but do you actually know what it does? It says that it will use “your most recent settings that worked,” but that could mean a variety of things.
Then there is the Windows System Restore, which by the name would almost make people assume it does something similar to the Last Known Good Configuration, but in reality they are pretty different. Lets see how the two of them differ, and when you would want to use each of them.
–Last Known Good Configuration–
Each time you successfully startup your computer, Windows saves any system-related settings to the Windows Registry. Some of the information that is written to the Registry is in regards to device drivers and services that are used by Windows.
When you choose to use the Last Known Good Configuration mode all of the settings contained within the
HKLM\System\CurrentControlSet Registry key will be restored to the last state when you’re computer booted up successfully. This will not modify any files, but it will be able to point the system back to older drivers, assuming that they are still accessible on the machine.
Using the Last Known Good Configuration…
- Start your computer.
- When you see the “Please select the operating system to start” message, press the F8 key.
- When the Windows Advanced Options menu appears, use the ARROW keys to select Last Known Good Configuration (your most recent settings that worked), and then press ENTER.
Use Last Known Good Configuration if…
- The last time you started Windows you didn’t have any issues.
- You install a new device driver, restart Windows, and the computer will no longer boot. By reverting back to the Last Known Good Configuration you will restore the settings so that they point back to the old driver.
- You disable a driver that turns out to be more critical to the operation of Windows. By reverting back to the Last Known Good Configuration you will restore the settings back to when the driver was still enabled.
DON’T Use Last Known Good Configuration if…
- Windows won’t boot because you deleted some system files.
- You copy a new driver over top of an old one. Switching to the last known good control set will not undo anything since the configuration never changed.
- Windows boots up, a user logs in, and then Windows freezes. By this point it is too late because Windows has already written over the Last Known Good Configuration backup.
System Restore was haphazardly introduced back in Windows Millennium Edition, but wasn’t actually found to be useful until Windows XP was released. It’s progressively gotten better as more versions of Windows have been released, and in Vista it includes some new features.
Restore points (a.k.a. checkpoints) are, by default, created every 24 hours or when the user manually creates them. Aside from that restore points are also automatically created when some applications are installed, Windows Updates are installed, or non-signed drivers are installed.
System Restore is very selective in what it backs up. It keeps track of changed system files (extensions: EXE, BAT, DLL, etc…), Windows Registry, drivers, and more. It never touches file formats related to things like documents, email, music, and a few others that aren’t critical to the system’s operability. It will also ignore things placed in “My Documents” giving you a little reassurance that you won’t wipe out your documents during a restoration.
CAUTION: It’s important to know that all programs installed after the selected restore point will be uninstalled when rolling back your system using System Restore.
Using System Restore…
- Open System Restore by clicking the Start button, clicking All Programs, clicking Accessories, clicking System Tools, and then clicking System Restore.
- Choose a restore point and proceed through the wizard.
One of the nice things about System Restore is that a checkpoint is also created before you proceed with the restoration. If using a restore point didn’t help you’ll always be able to jump back.
Use System Restore if…
- Problems started to occur after you installed an application, Windows Update, or a driver.
- You accidentally removed or modified an important system file that is causing the system not to function properly.
DON’T Use System Restore if…
- You have installed an application since the selected restore point, and you’re afraid of losing the application itself.
- You have important files placed throughout your computer, and you’re not sure if System Restore will ignore them. Place all of your personal files into the “My Documents” folder to ensure that they are protected.