This error occurs when Windows 7 has a problem, tries to resolve it by backing up the user profile in the registry and creates a new faulty one for the user. This fix restores the original entry in the registry. The problem is that you cannot log on to your computer to edit the registry. Therefore this is a two part fix, the first part is to enable the computers built-in administrator user and the second part is the registry fix. I have added a third part which is what else to try. I have had 100% success with this fix however so far only five machines have come in to be fixed. I have never had to try part 3…. so far!
Part 1 – Activating the built-in administrator user
1. You need to start the computer in “Safe Mode with Command Prompt” to do this start your computer and hit F8 multiples times after the initial BIOS screen. You should see see a menu screen. If you see the Windows splash screen then hold down the power button for ten seconds and then repeat this step.
2. Highlight Safe Mode with Command Prompt and hit [Enter]. Try logging in there. If it still doesn’t work, then go to step 17.
3. If you are able to login, once a command prompt pops up, type:
net user administrator password /active:yes
You can specify whatever password you want for the administrator account.
4. If you get a message saying “The command completed successfully”, then restart your computer by typing: shutdown -r. If not go to step 17.
Part 2 – Editing the registry
5. Boot up again pressing F8, but this time select Safe Mode – not the Command Prompt.
6. You will be able to login as Administrator with the password you set in Step 3.
7. Hold down [Windows logo] key + [R] key.
8. Type regedit[Enter]
9. Once in the registry editor, use the left window to navigate to the key:
HKEY_LOCAL_MACHINE
SOFTWARE
Microsoft
Windows NT
CurrentVersion
ProfileList
10. In the left pane, find the one that starts with S-1-5….. and ends with .BAK. If you don’t find one, skip to step 15.
11. Right click it and click Rename, then change the .BAK to .BK
12. Right click the one with the same numbering but without the .BAK and add .BAK to the end.
13. Right click the one that you renamed to .BK and click Rename, delete the .BK
14. What you are doing is switching the one with .BAK to the one without. This should be enough to fix this problem.
Part 3 -What else to try
15. If you didn’t find a .BAK entry in the registry then open Windows Explorer to:
C:\Users\Default\AppData\Local\Application Data
You will have to show hidden and system files to do this.
16. If you find another Application Data below the one you’re on, then delete it. That should fix your problem.
17. If you can’t login in Safe Mode, then reboot and hit [F8] until you see the menu again, then select “Repair Your Computer”.
18. Wait until all Windows Files finish loading, then hit Next when it asks keyboard language.
19. Try logging in here. Select your user from the drop-down menu, and type the password, then jump to step 23
20. If that still doesn’t work, then if you have your Windows Installation DVD still, put it in and restart your computer.
21. Hit the correct function key to boot from the DVD or change the boot order in the BIOS (Setup).
22. Choose keyboard language then hit next. Find “Repair Your Computer” from a little below the centre left.
23. Choose Open Command Prompt and type:
net user administrator password /active:yes (again you can specify a password)
24. Close the command prompt and click Restart and jump to step 5
Finally
To disable the administrator account, type this in an elevated command prompt:
net user administrator /active:no
Good luck!