The Registry Checker By Carolyn Z. Gillay Carolyn Z. Gillay is the author of numerous textbooks for computer classes. This article is an excerpt from her latest book, Windows 98: Concepts & Examples. Download the PDF file for this article. Windows 98 provides a new utility called the Registry Checker. Each time you start your computer, it will automatically scan the Registry. It maintains one backup for each day. It maintains up to five compressed backups of the Registry that have been successful in booting the system. Five is the default value, but it can be increased to 99 copies. When you start your system, the Registry Checker automatically scans the Registry for errors. If it finds a problem, it will automatically restore the most recent Registry from a backup copy. The Registry Checker also performs other functions. The Registry grows in size, which decreases performance. The Registry Checker also determines the amount of free space in the Registry and compacts it, if necessary. In addition to running automatically, you can run the Registry Checker manually. It has two flavors: ScanRegW, which is the Windows-based program, and ScanReg which is the command line MS-DOS-based program. ScanRegW scans the Registry for corruption and determines if it requires optimization. It backs up USER.DAT and SYSTEM.DAT, WIN.INI, and SYSTEM.INI. If ScanRegW finds a problem, it will prompt you to restart your computer to fix the problem. This restart causes ScanReg to run and either restore the Registry from a known good backup, or, if it can find no good backup, to repair the current Registry. It will also optimize the Registry. The table below compares the differences between the two programs. ScanRegW versus ScanReg  Function ScanRegW  ScanReg  Real or protected mode  Protected mode  Real mode  Scan registry  Yes Yes  Fix registry  No Yes  Backup registry  Yes Yes  Runs in safe mode  Yes Yes Compresses backup  Yes No  Runs automatically  Yes—every time you start the computer  Yes—if a registry problem is found  Restores the registry  No Yes One of the functions of the Startup Disk is to allow you to boot to the command line prompt. When you do so, you can run ScanReg at the command line to repair or restore a corrupt Registry. You may also run the Registry Checker from the System Information window, located in System Tools. Restoring the Registry The only time you will need to choose which Registry to restore is in case you install something on your computer that keeps it from booting and the Registry is not corrupt. You would, in this case, use ScanReg /Restore, which will provide a list of known good .CAB files and will indicate whether the system configuration files stored in the .CAB files have successfully started Windows 98. You should choose the .CAB file that was most recently used to start Windows 98 unless you are certain that a specific .CAB file will successfully start Windows 98; for instance, one you created by manually running ScanRegW.

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