See if this helps, lifted from another forum.

Okay, the problem is your Registry got seriously corrupted or you lost an entire hive.

You lost HKEY_LOCAL_MACHINE\SYSTEM

I would have recomended you try the Last Known Good Configuration.

If not, you can extract the necessary registry files from System Resore. You see it makes a backup of your registry at each restore point.

What you can do is cd to System Volume Information assuming the ACL Lets you go there. If not you will need to use cacls to change the permissions and add administrator to that NTFS space.

Next, browse to the newest restore point. Sort them by date and find the snapshot folder.

For me

C:\System Volume Information\_restore{C124B6EE-F5E1-4677-A471-C23BE17217FF}\RP541\snapshot

That is Why XP refused to start.

In there, you will find something that looks like _HKLM_System

or something to that extent.

make a backup of c:\widnows\system32\config\system

To fix
Just copy and rename it all in one go with the copy commnd.

e.g.

While in the folder

copy _HKLM_System c:\windows\system32\config\system

Now, you have a partially incorrect HKEY_LOCAL_MACHINE\System because it is not consistent with the rest of the registry.

However, it should be good enough to either boot the system or at least you will get another error.

The system will probably start up in normal mode now 99%, but I give it a 100% that it will startup in safemode.

When the system starts, you may see something to the extent of "A Service failed to initialize properly" or something like that because that is the area where the services are stored...

Now that you are in safemode, run system restore and pick the most recent restore point. That will restore your entire registry to a known good point!!!

Windows should run just fine from that point out.

-Jbirk