For backup and restore / edit Registry files:
Backup Utility: Backup is a utility included with Windows Server 2003 that you can use to back up and restore the entire registry. Backup can create backup files on many kinds of media, including local and networked disk resources. Backup can create backups of files that are open and in use, in addition to closed files, so it is your best choice for creating a complete backup copy without disturbing active users or processes.
1. To back up the registry by using Backup, when you select the drives, files, and folders that you want to include in a backup set, also select System State. When you choose to back up or restore System State data, all of the data that is relevant to your system configuration is backed up or restored.
2. To restore the registry by using Backup, restore System State.
For more information about using the Backup utility and System State to backup and restore your registry, see Backup overview and System State data in Help and Support Center for Windows Server 2003.
3. Ntbackup.exe : Ntbackup.exe is a command-line tool that allows you to create backup files of your registry. Ntbackup.exe cannot be used to restore your registry, but Ntbackup.exe files can be used with Backup to perform the restoration.
4. Manually Copying Files: can back up the registry by manually copying the registry files from their storage location in the file system to another location. However, to make use of these files in the event of registry failure, you need to be able to start the computer by using an operating system that can read both the file system of the backup media and of the partition in which the non-working operating system is installed. To copy these files, you must shutdown the operating system and use boot disk or utility that can access and read the file system. To back up the registry by manually copying files, copy all files in Systemroot\System32\Config to removable media, a network share, or a compatible partition. Be sure to note the actual path to these files, because Systemroot resolves differently when your computer is running a different operating system.
To restore the registry by manually copying files, copy the backed up registry files from their backup location to their original location (the location indicated by Systemroot \ System32\Config when the associated operating system was running). This overwrites all registry settings with those in the backed up registry files.
5. Regedit.exe and Reg.exe : Regedit.exe and the command-line tool Reg.exe allow you to back up and restore individual subkeys, keys, or whole subtrees by saving parts of your registry as files on your computer, removable media, or network shares.
Reg.exe can only be used to modify local registries, but Regedit.exe can be used to modify both local and remote registries. The tools are RegBack.exe, RegRest.exe, & Regedt32.exe
There is must a security issue. Before doing anything must take registry backup via File > export > Save
Hope after reading this article you get you all of your answers!