How to Rebuild the Default Windows REG.DAT File

During installation of Microsoft Windows, the REG.DAT file is not copied from the original distribution disks. Instead, REG.DAT is built using the Windows Registration Information Editor (REGEDIT.EXE) and the SETUP.REG file (located in the Windows SYSTEM subdirectory) during Setup.

If the REG.DAT file is corrupted, one of the following error messages may be displayed: If, for whatever reason, the REG.DAT file is corrupted or deleted, you can rebuild the file using the information below.

The REG.DAT file contains information about file associations and OLE objects. The Windows 3.1 Setup program calls the Registration Information Editor to add default associations (for Paintbrush, Notepad, and so on) and objects (Packager, Paintbrush, and Sound Recorder).

Rebuilding the REG.DAT File for Applications Included with Windows

You can manually create a new REG.DAT file or restore the defaults by following the steps below.

Notes

• Be sure to rename your existing REG.DAT file before you try to rebuild it.
• These steps assume your Windows directory is on drive C and is named WINDOWS.

1. Run Program Manager or File Manager.
2. From the File menu, choose Run.
3. In the dialog box, type the following:
   regedit /u c:\windows\system\setup.reg
   NOTE: A message appears to confirm that the information has been registered. The database now contains the original registration information that was installed with Windows. To rebuild the REG.DAT file for other applications, see the "Rebuilding the REG.DAT File for Other Applications" section below.
   
   
4. Choose OK.
   
   NOTE: You may need to exit and restart Windows in order to see the REG.DAT file displayed in File Manager and execute the following step.
5. In File Manager, select the REG.DAT file found in the Windows program directory, then choose Associate from the File menu and associate Files with Extension: DAT and REG with REGEDIT.EXE.
   
   NOTE: When you removed the old REG.DAT file, you also removed your file associations list; therefore, you must choose REGEDIT.EXE using the Browse button.
6. Exit and restart Windows.

Rebuilding the REG.DAT File for Other Applications

For applications other than the Windows-based programs included with Windows 3.1, the technique varies for rebuilding REG.DAT. Some applications, such as Microsoft Word 2.0 for Windows, rebuild their entries every time the application is started. Other applications may register themselves only during their setup processes.

NOTE: If you are using Word 2.0 for Windows, make sure to include the path to the Word for Windows program directory and the WW20.REG file located there (for example, C:\WINWORD\WW20.REG) so that the registration database is updated.

If the application includes an .REG file, you can add that information to the registration database. To do so, use any of the following methods:

• Choose Merge Registration File from the File menu in the Registration Information Editor. Then select the .REG file for the application to be added to the database and choose OK.
  
  -or-
• Use the same steps described above, substituting the name of the .REG file. Otherwise, consult the application's documentation or contact your vendor for more information about rebuilding the REG.DAT file.
  
  -or-
• Run Windows File Manager and double-click the application's .REG file.

If you need to rebuild the registration database for all your applications, use the following steps:

1. From the File menu in File Manager, choose Search.
2. Search for *.REG from C:\. Ensure that the Search All Subdirectories check box is selected before you choose OK.
3. Run SETUP.REG by double-clicking the file icon or by highlighting it and then pressing ENTER.
4. Run every other .REG file brought up by the File Manager search (just as you did in step 3). Remember to search each available hard disk for .REG files so that every program will be registered in the new REG.DAT file.

For instructions about registering Microsoft Office version 4.x applications, query on the following words in the Microsoft Knowledge Base: Additional information about Registration Information Editor is available in Windows 3.1 Help.

"Microsoft Windows Resource Kit for Operating System Version 3.1," Chapter 11, page 360