[Hack&Lube]

If you can get to a command prompt (usually via the installation CD in repair/recovery or via using the drive in another computer), you can type these commands to copy the backups over the corrupted hives:

copy C:\windows\system32\config\regback\system c:\windows\system32\config\system

copy C:\windows\system32\config\regback\software c:\windows\system32\config\software

copy C:\windows\system32\config\regback\security c:\windows\system32\config\security

copy C:\windows\system32\config\regback\sam c:\windows\system32\config\sam

copy C:\windows\system32\config\regback\default c:\windows\system32\config\default

This takes the backups in the regback folder and writes them over the currently used registry files (which are damaged or corrupted).

Of course if you opened the drive in another computer, you could just drag/copy/paste the files in the GUI too.

So really it's just a simple issue of one or more of those five files being damaged so you just have to copy the backups over top of them. The problem is that you can't boot into Windows so you have to load an operating system via the CD or use the operating system of another computer to access the file system to even do a simple copy of 5 files.