ERUNT (Emergency Recovery Utility NT) is a free program that allows you to keep a complete backup of your registry and restore it when needed.

Backing up the registry with ERUNT
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Note: To ensure proper operation of ERUNT, you should be logged in as a system administrator.

Start ERUNT, confirm the Welcome message.

Type in the name of a restore folder where the backed up registry files should be saved, or click "..." to browse your computer's drives and select a folder. You can also simply leave the default, which is afolder named ERDNT inside your Windows folder, the advantage being that you have access to this folder from the Windows Recovery Console in case Windows does not boot anymore.

Note that in the folder edit field, ERUNT by default appends a folder named the current date to the restore folder, which allows you to keep as many registry backups as you wish in the same restore folder, separated into the different creation dates. This feature, as well as the appearance of the date string, can be configured via the ERUNT.INI file, described later in this document. If you want the registry backup to be created directly in the folder you select, you can also simply remove the date from the folder edit field before clicking "OK".

Next, select the backup options:

- System registry: The current system registry, usually consisting of the files DEFAULT, SAM, SECURITY, SOFTWARE, and SYSTEM.

- Current user registy: The registry files for the currently logged-on user, usually NTUSER.DAT and USRCLASS.DAT.

- Other open user registries: Sometimes Windows has a few other user registries in memory. Examples for this are "generic" registries, e.g. for user "EVERYONE", or registries of other users if you use Fast Task Switching in Windows XP. Check this option to backup all these additional user registries (if found) as well.

Click "OK" and wait until the backup process is complete. (Note that depending on your system configuration this may take some time, and
that the first bar is NOT a progress bar, just an indicator that the program is still running.) The ERDNT program for later restoration of the registry is automatically copied to the restore folder.