Previously, I showed you how you could restore an unbootable system to a functional state by using the Last Known Good Configuration option. In this article, I'll explain some other useful recovery techniques: device driver rollback and System Restore.
Device driver rollback
Perhaps the most commonly made catastrophic change in Windows XP involves the installation of an invalid device driver. Windows takes steps to prevent invalid device drivers from being installed, but the driver-checking mechanism isn't perfect and can easily be circumvented. When someone installs an invalid device driver, the end result can be anything from a single hardware device not working to the entire system being rendered unbootable.
Fortunately, recovering from this type of problem is relatively easy. The technique that I am about to show is known as device driver rollback. It will work in most situations, assuming that you have installed the invalid device driver in the usual manner. If you've done something crazy, like renaming an invalid device driver so that it matches the name of a good device driver and then overwriting the good file with the invalid file, then this technique won't work.
The first thing I recommend doing is booting the system in Safe Mode. Safe Mode uses a minimal driver set, so even an otherwise unbootable system should be able to boot into Windows. You can access Safe Mode by pressing the F8 key during the earliest phase of the Windows boot process, and then selecting the Safe Mode option from the boot menu.
Once Windows has booted into Safe Mode, things will probably look a little strange. That's because Windows is using a really low-end video driver that is designed to work with all video adapters and all monitors. Just ignore the resolution and color limitations, and open the Control Panel.
When the control panel opens, click on the Performance and Maintenance link, followed by the System link. When you do, Windows will open the System Properties sheet. Select the sheet's Hardware tab and click the Device Manager button to open it.
When the Device Manager opens, scroll through the list of devices until you find the device that has an invalid driver associated with it. Next, right click on that device and choose the Properties command from the resulting shortcut menu to access the device's properties sheet. Finally, select the sheet's Driver tab and click the Roll Back Driver button. Windows will now revert the device driver to the previous version.
Device drivers aren't the only system change that can have catastrophic results. There are a number of activities ranging from registry changes to software installations that can cause problems. In such situations, often you can use System Restore to take your computer back in time so that the configuration is as it was prior to the catastrophic change.
Contrary to the sound of its name, System Restore does not involve restoring a backup. Instead, Windows creates system restore points just prior to various types of configuration changes. If the change is catastrophic, then you can revert back to the system restore point. System Restore isn't perfect -- nor is it a good substitute for a normal backup -- but it can still be very helpful.
Assuming that your system has been rendered unbootable, you should begin the restore process by booting to Safe Mode in the manner that I discussed earlier. Once Windows boots, log in as an administrator and select the following commands from the Start menu: All Programs | Accessories | System Tools | System Restore.
When the System Restore application loads, choose the Restore My Computer to an Earlier Time option and click Next. You will be taken to a screen that allows you to choose a point in time that you want to revert the system to. Keep in mind that reverting to a restore point only effects the system's configuration, not the data that is stored on the system. Choose the restore point that you want to use, and click Next to begin the restoration process.
So now you know two more techniques that can be used to reverse catastrophic configuration changes. In the final article of this series, I will offer a few other, more complicated options for restoring Windows XP.
|Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Windows 2000 Server, Exchange Server and IIS. He has served as CIO for a nationwide chain of hospitals and was once in charge of IT security for Fort Knox. He writes regularly for SearchWinComputing.com and other TechTarget sites.|