Windows stores information about how it is configured in a centralised database called the Registry. The Registry not only contains information about how Windows is set up on your PC, but also how each application you have installed is configured.

Storing all this information centrally makes it easy to adjust settings and keep track of configuration information, but it makes for one giant vulnerability in the operating system. If your Registry gets damaged your system may be rendered unusable. Even minor Registry errors can cause programs to crash or behave erratically.

That's why whenever you use the Registry Editor (regedit) to change settings within the Registry, you're admonished to make a backup first. No doubt you've seen this warning frequently.

That's all very well, but what do you do if something does go wrong with your Registry? How do you restore that backup?

Windows gives you a variety of ways to recover from a damaged Registry. We'll look at the simplest way to get you back up and running after a disaster. But before that, let's look at the easiest way to ensure you have a current backup of your Registry.

Automatic backups

The good news is Windows 98 and Me automate the process of creating a Registry backup (Windows XP does, too, although the Registry is organised differently under Windows XP and Windows 2000). Once each day, the Windows-based Registry Checker tool (scanregw.exe) backs up the Registry – which consists of the two files user.dat and system.dat and, in some cases, a third file, policy.pol as well – to the hidden \Windows\Sysbckup folder. (Note: To make this hidden folder visible, open Windows Explorer and select Folder Options from the Tools or View Menu. Click the View tab and, under Hidden Files, select Show All Files and remove the tick beside Hide File Extensions For Known File Types.)

The backed up Registry files are placed in a Cabinet (CAB) file called RB0nn.cab, where nn is a number from 01 to 99, together with backups of two other important system files, system.ini and win.ini. By default, the Registry Checker makes a maximum of five Registry backups, named RB001.cab - RB005.cab. When five backups already exist, the Registry Checker creates the next backup by overwriting the oldest CAB file. You can thus determine the most recent Registry backup by comparing the file dates of each of the CAB files.

Manual backups

You can use the Registry Checker to create a backup of the Registry at any time. This is a good idea if you're about to edit the Registry and want to ensure you can get yourself back up and running if anything goes wrong. Before you use the Registry Editor, run the Registry Checker manually:

  1. Click Start -> Run, type scanregw in the Open box and click OK.
  2. The Registry Checker will check the Registry for errors and, if none are found, will tell you that a backup of the Registry has already been made today. It will offer to make an additional backup. Click Yes to create this new backup then click OK once the backup has been created.

Restoring the Registry

If something goes wrong and you need to replace the current version of the Registry with one of your backups, here's how:

  1. Start your computer in MS-DOS mode. If you're using Windows 98, do this by restarting the computer and holding down the Ctrl key (on some computers, you use the F8 key) until the boot menu appears. From the boot menu select Command Prompt Only. If you're using Windows Me, you'll need to use your Windows Me Startup floppy disk (you do have one, don't you?). Restart your computer with the floppy disk in the drive and choose Minimal Boot. If you don't have a Windows Me Startup disk, make one now before disaster strikes, by clicking Start -> Settings -> Control Panel -> Add/Remove Programs -> Startup Disk and following the prompts.
  2. At the DOS prompt, type:

scanreg /restore

This runs the DOS-based version of the Registry Checker tool.

  1. Select a backup from the list provided – usually the most recent backup is the best option – and press Enter.
  2. Press Enter to restart your computer (remove the boot disk from the floppy drive first if you've used one).

© 2002, Rose Vines  

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