

However, starting with Windows 7, Microsoft stopped supporting the Scanreg.exe tool. In earlier versions of Windows, the Windows Registry Checker tool (Scanreg.exe) was available to automatically back up the registry, and check the registry for invalid entries, empty data blocks, and other errors. If your Windows does not boot correctly due to the damaged registry, you need to check the integrity of the registry files.

SYSTEM (HKLM\System) - settings for computer’s hardware, settings for Windows services, drivers, and other low-level information.SECURITY (HKLM\Security) - Windows security settings.SOFTWARE (HKLM\Software) - the settings of various applications and the Windows OS itself are stored, common to all users.SAM (HKLM\SAM) - the settings of all Windows security principals are stored.DEFAULT (HKEY_USERS\DEFAULT) - a template with user settings used when creating new accounts.Below is a list of files and registry hives that these files are loaded into when Windows boots (as you see them in Registry Editor):
