Description of the Windows Registry Checker Tool (Scanreg.exe)

ID: Q183887

The information in this article applies to:

SUMMARY

When you start your computer successfully, Windows Registry Checker (Scanreg.exe) creates a backup of system files and registry configuration information (including user account information, protocol bindings, software program settings, and user preferences) once daily. Files that Windows Registry Checker backs up include System.dat, User.dat, System.ini, and Win.ini. This article provides a description of the Windows Registry Checker Tool.


MORE INFORMATION

Windows Registry Checker automatically scans the system registry for invalid entries and empty data blocks when it is started. If invalid registry entries are detected, Windows Registry Checker automatically restores a previous day's backup. This is equivalent to running "scanreg /autorun" (without quotation marks) from a command prompt. If no backups are available, Windows Registry Checker tries to make repairs to the registry. This is equivalent to running "scanreg /fix" (without quotation marks) from a command prompt. If the registry contains more than 500K of empty data blocks, Windows Registry Checker automatically optimizes it.

Windows 98 Setup runs the Windows Registry Checker to verify the integrity of the existing registry before it performs an upgrade. If it detects registry damage, it tries to fix it automatically.

The protected-mode version of the Windows Registry Checker (ScanregW.exe) can create a backup of the system files and scan the registry for invalid entries. If invalid entries are detected, it refers to the real-mode version of the Windows Registry Checker (Scanreg.exe) for a resolution.

The Windows Registry Checker can be configured with the Scanreg.ini file. Settings that you can configure include:

For more information about the Scanreg.ini file, see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: Q183603
TITLE : How to Customize Registry Checker Tool Settings

To start the Windows Registry Checker, click Start, click Run, type "scanregw.exe" (without quotation marks) in the Open box, and then click OK.

NOTE: To use Windows Registry Checker with the /restore parameter, it must be run from a command prompt running outside of Windows. When you do so, you can choose up to five registry backup files listed for you to restore.

To restore individual files, following these steps:
  1. Click Start, point to Find, and then click Files Or Folders.


  2. In the Named box, type rb0*.cab, and then click Find Now.


  3. Double click on the cabinet file that has the correct file you want to restore.


  4. Right-click the file you want to restore, click Extract, and then choose the folder where the new file is to be placed.


Known Issues for Windows Registry Checker

If your registry contains an entry that references a file (such as a .vxd file) that no longer exists, it is not repaired by Windows Registry Checker. Such errors are not typically damaging, and if you want to you can manually remove the entry. For information about such errors, see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: Q132008
TITLE : Err Msg: Cannot Find a Device File That May Be Needed...

The amount of conventional memory required by the Registry Checker is determined by the size of your registry. You may require 580K or more of free conventional memory to complete the repair process. If you encounter an Out of Memory error message, optimize your free conventional memory. For information about optimizing memory, see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: Q134399
TITLE : How to Increase Conventional Memory for MS-DOS-Based Programs

NOTE: Extended memory is required for Windows Registry Checker to operate properly, so it does not run when you start your computer in Safe Mode Command Prompt Only. The exception to this is "scanreg /restore" which is the only scanreg function that can run without XMS memory.

Additional query words: 98 


Keywords          : kbenv kbtool win98 
Version           : WINDOWS:
Platform          : WINDOWS 
Issue type        : kbinfo

Last Reviewed: February 2, 1999