Many IT pros don’t know that Windows 98 comes with a built-in registry backup tool called Registry Checker. This hidden tool works in the background and once a day scans the Windows 98 system’s registry for errors. If the registry is error-free, the Registry Checker automatically backs up the registry. If an error is found, the Registry Checker automatically restores the most recent copy of the registry.

If the registry becomes so badly mangled that you can’t even start Windows 98, the Registry Checker can provide you with a method of manually restoring the registry from within a DOS environment. However, since the Registry Checker works in the background and automatically performs its operations, it’s possible that you would never even know that it exists. As such, you would also never know that recovering a Windows 98 system from a corrupt registry could be an easy operation. To help you uncover some of the hidden tools of the Registry Checker, I’ll examine this tool in more detail. As I do, I’ll also show you how to manually restore the registry from within a DOS environment.

The origins of System Restore

If in addition to supporting Windows 98 you also support Windows Me or Windows XP, you’ll probably recognize that some of the features in the Registry Checker remind you of another tool. The Registry Checker set the foundation for the System Restore tool in Windows Me and XP. 

Background monitoring
The Registry Checker works behind the scenes and monitors the condition of the operating system’s registry every day. As it performs its daily backup operations, the Registry Checker stores the backups in the hidden Windows\Sysbckup folder. If you were to take a look in that folder, you’d discover that the Registry Checker actually keeps five backup copies of the Registry and that each of these copies is stored in a compressed format. The compressed backups are stored in files named rb000.cab, rb001.cab, and so on, as shown in Figure A.

Figure A
The Registry Checker compresses the backup copies as it stores them in the hidden Windows\Sysbckup folder.

Performing a manual backup operation
Even though the Registry Checker performs backups of the registry each and every day, there may be occasions when you want to manually back up the registry as a precautionary measure. For example, you might want to perform a manual backup right before you install new hardware or software. Or, you may be getting ready to use the Registry Editor to apply a new registry hack. By performing a manual backup of the registry, you’ll be able to restore it to a good state if anything goes wrong and the Registry becomes damaged. As you can imagine, being able to avert such a disaster with a simple restore procedure could save you hours of wasted time and frustration. Fortunately, the Windows 98 operating system provides you with a means of doing so.

You can find and launch the Registry Checker from within the System Information tool. To begin, you’ll launch the System Information utility from the Programs | Accessories | System Tools menu as you normally would. Then, once you have the System Information utility up and running, pull down the Tools menu, and select the Registry Checker item. As soon as you do, the Registry Checker will quickly scan your Registry for errors, as shown in Figure B.

Figure B
As soon as you launch it, the Registry Checker immediately checks the registry for errors.

Alternate launch sequence

In addition to launching the Registry Checker from the Program | Accessories | System Tools | System Information | Tools menu, you can launch it from the Run dialog box. To do so, press [Windows]R to open the Run dialog box and type Scanregw.exe in the Open text box.

If the Registry Checker finds that the registry is in perfect health, you’ll be prompted to make a backup, as shown in Figure C. As you can see, this dialog box also informs you that the registry has already been backed up. To continue, click the Yes button to replace the oldest backup file with the new one.

Figure C
Once the Registry Checker certifies that the registry is in perfect health, it prompts you to make a backup.

As the Registry Checker goes to work, you’ll see what amounts to a progress window, but without the gas gauge animation, as shown in Figure D. The lack of animation here is not a design flaw; it’s actually due to the fact that the Registry Checker runs in the background and performs its job very quickly. When the process is finished, you’ll be informed that the backup operation is complete.

Figure D
Registry Checker displays a bare-bones progress window as it does its job.

Performing a manual restore operation
The Registry Checker normally works in the background and is supposed to automatically restore the registry from the last good backup in the event that it discovers a problem. However, there are situations where you would need or want to manually restore the Registry.

For example, Windows 98’s Registry could become so damaged that you’re unable to start the operating system. Then again, you may encounter a situation in which the operating system starts fine, but then out of the blue begins acting strange. In either of these cases, performing a manual restore operation of the Registry should solve your problem. To do so, you’ll use the DOS version of the Registry Checker, which is called the Microsoft Registry Checker.

Run it immediately

Keep in mind that for a manual registry restore procedure to be successful, you need to perform the operation as soon as you discover a problem that you suspect is caused by a corrupt registry. If you reboot your system several times before running a manual restore operation, you may overwrite and thus lose the good backup of the registry.

To manually restore the Registry, boot your system to an MS-DOS prompt on system startup. To do so, press [F8] or [Ctrl] when you hear your system’s initial beep. In a moment you’ll see the Windows 98 Startup menu and will select the Command Prompt Only option.

Once you see the MS-DOS prompt, type in the command line:
Scanreg/restore

Doing so will launch the DOS version of the Registry Checker, as shown in Figure E. 

Figure E
You’ll launch the DOS version of the Registry Checker in order to perform a manual restore operation.

As you look at the list of backups that the Microsoft Registry Checker displays in the scrolling list box, you’ll notice that the information about the backups includes not only the date on which the backup was created, but also whether the backup has been used to successfully start Windows 98. As I mentioned, the Registry Checker maintains a series of five registry backups. In theory, the backup named rb000.cab should be the most recent backup. However, that’s not always the case. So you need to pay attention to the date as well as the filename.

As a general rule you should use the backup that was most recently used to start the system. However, if you manually created a registry backup just prior to the occurrence of the problem, you’ll want to select that backup—even though it hasn’t been used to start the system because you know for sure that it is based on a good copy of the registry.

To restore the registry, use the arrow keys to select from the list the backup file you want to use and press [Enter]. When you do, the Microsoft Registry Checker first backs up the current copy of the registry (for safety reasons) and then it will restore the registry from the backup. As soon as it does so, you’ll see the screen shown in Figure F, which informs you that the registry has been restored and prompts you to restart your system. To do so, simply press [Enter].

Figure F
Once the restore operation is complete, the Microsoft Registry Checker will prompt you to restart your computer.

Using the Registry Checker to optimize your registry
If you’re like most computer users, you’re always on the look out for ways that you can optimize your system’s performance. You probably run Disk Defragmenter on a regular basis in order to move all available empty space to the end of the drive and keep the files on your hard disk in contiguous order. You know that doing so makes launching applications and opening data files much more responsive. So why not apply that same reasoning to the registry?

You can use the Registry Checker to optimize the registry by removing unused space, thus making the registry’s operation much more efficient. To do so, you’ll first need to boot your system to an MS-DOS prompt (as explained earlier in this article), as you’ll be using the DOS version of the Registry Checker to optimize the registry.

Once you see the MS-DOS prompt, type in the command line:
Scanreg/opt

Doing this will launch the DOS version of the Registry Checker—however, you won’t see any interface on the screen. Instead, the Registry Checker will go straight to work and remove any unused space in the registry.

More information on the Registry Checker
If you want to learn more about the Registry Checker, I suggest that you check out the following Microsoft articles: