ERUNTgui: Backup, restore and optimize Windows Registry

Before modifying anything in the Windows Registry, it is always a good idea to back it up. We have already blogged about the different ways to back up the Registry or its Hives, along with how to restore or maintain the registry.


One of the tools we had discussed there was the popular and dependable ERUNT.

However the ERUNT & NTREGOPT  UI was spartan and not very user friendly.

Enter ERUNTgui !

ERUNTgui is a graphic user interface for the popular registry backup and restore program ERUNT and NTREGOPT.

ERUNT and NTREGOPT in their current versions 1.1j are still compatible with Windows 7, but as in Vista, they will only work correctly if you turn off User Account Control in Windows’ Control Panel (move the slider to the lowest position).

Also, a problem has been discovered which on many systems causes ERDNT and NTREGOPT to display a “RegSaveKey: 3” error when optimizing / restoring the BCD00000000 hive. The cause is that after a clean install of Windows 7, the BCD part of the registry which contains Windows’ boot configuration data resides on a hidden system partition with no drive letter assigned in Explorer.

You can simply ignore this error and continue, or as a workaround, open Disk Managemant in Control Panel and right-click on the partition displayed as “System Reserved” to assign a drive letter. Future versions of ERUNT and NTREGOPT will of course have these issues fixed.

Regbak and how to Back Up the Windows Registry may also interest you. To learn how to recover registry keys, go here.

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Anand Khanse is the Admin of, a 10-year Microsoft MVP Awardee in Windows (2006-16) & a Windows Insider MVP. Please read the entire post & the comments first, create a System Restore Point before making any changes to your system & be careful about any 3rd-party offers while installing freeware.