Question : Mouse and Keyboard don't work after attempting to repair registry in Dell XPS (Windows XP Home)

Hello, I'm trying to fix a computer - I was told that a teenager was using it and the computer stopped working. At the state I received it, upon load, I got the following error message: windows could not start because the following file is missing or corrupt: \windows\system32\config\system

Based on that, I proceeded to attempt at fixing the issue using the steps in this Microsoft article: http://support.microsoft.com/kb/307545

This is as far as I got:

   1. Insert the Windows XP startup disk into the floppy disk drive, or insert the Windows XP CD-ROM into the CD-ROM drive, and then restart the computer.
      Click to select any options that are required to start the computer from the CD-ROM drive if you are prompted to do so.
   2. When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
   3. If you have a dual-boot or multiple-boot computer, select the installation that you want to access from the Recovery Console.
   4. When you are prompted to do so, type the Administrator password. If the administrator password is blank, just press ENTER.
   5. At the Recovery Console command prompt, type the following lines, pressing ENTER after you type each line:
      md tmp
      copy c:\windows\system32\config\system c:\windows\tmp\system.bak
      copy c:\windows\system32\config\software c:\windows\tmp\software.bak
      copy c:\windows\system32\config\sam c:\windows\tmp\sam.bak
      copy c:\windows\system32\config\security c:\windows\tmp\security.bak
      copy c:\windows\system32\config\default c:\windows\tmp\default.bak

      delete c:\windows\system32\config\system
      delete c:\windows\system32\config\software
      delete c:\windows\system32\config\sam
      delete c:\windows\system32\config\security
      delete c:\windows\system32\config\default

      copy c:\windows\repair\system c:\windows\system32\config\system
      copy c:\windows\repair\software c:\windows\system32\config\software
      copy c:\windows\repair\sam c:\windows\system32\config\sam
      copy c:\windows\repair\security c:\windows\system32\config\security
      copy c:\windows\repair\default c:\windows\system32\config\default
   6. Type exit to quit Recovery Console. Your computer will restart.

Note This procedure assumes that Windows XP is installed to the C:\Windows folder. Make sure to change C:\Windows to the appropriate windows_folder if it is a different location.

If you have access to another computer, to save time, you can copy the text in step five, and then create a text file called "Regcopy1.txt" (for example). To use this file, run the following command when you start in Recovery Console:
batch regcopy1.txt
With the batch command in Recovery Console, you can process all the commands in a text file sequentially. When you use the batch command, you do not have to manually type as many commands.
Part two
To complete the procedure described in this section, you must be logged on as an administrator, or an administrative user (a user who has an account in the Administrators group). If you are using Windows XP Home Edition, you can log on as an administrative user. If you log on as an administrator, you must first start Windows XP Home Edition in Safe mode. To start the Windows XP Home Edition computer in Safe mode, follow these steps.

Note Print these instructions before you continue. You cannot view these instructions after you restart the computer in Safe Mode. If you use the NTFS file system, also print the instructions from Knowledge Base article KB309531. Step 7 contains a reference to the article.

   1. Click Start, click Shut Down (or click Turn Off Computer), click Restart, and then click OK (or click Restart).
   2. Press the F8 key.

      On a computer that is configured to start to multiple operating systems, you can press F8 when you see the Startup menu.
   3. Use the arrow keys to select the appropriate Safe mode option, and then press ENTER.
   4. If you have a dual-boot or multiple-boot system, use the arrow keys to select the installation that you want to access, and then press ENTER.

------------------------------

After loading in safe mode (or LKGC, or any mode for that matter), the welcome screen displays, but the mouse and keyboard no longer work. Note that they work fine to select F2, F8 or F12 on startup; just when the operating system actually loads, neither the keyboard nor mouse work at all. From what I have gathered, this could be due to a virus that potentially caused the issue. I removed and reinserted the battery on the motherboard as one solution to reset the BIOS (there were no jumpers on the pins next to the battery.)

I have no clue as to what may need to be done to get the mouse and keyboard working again. If anyone does, and can help me out, I would be very grateful!

Answer : Mouse and Keyboard don't work after attempting to repair registry in Dell XPS (Windows XP Home)

Try a Repair installation of Windows.
This leaves all your programs and data intact while reinstalling Windows.

1.  Boot the computer from your XP CD (if this won't boot, you may need to change the order of boot devices in BIOS setup).
2   Eventually you will see the "Welcome To Setup" screen. Press the Enter key to start Windows Setup.
3.  Be careful NOT to choose R, which is "To repair a Windows XP installation using the Recovery Console".
4.  Accept the License Agreement.
5.  Windows setup will search for existing Windows installations.
6.  Select the XP installation you want to repair (there is usually only one) and now press R to start the repair.

More complete instructions on how to do this, complete with pictures, are here:
http://www.michaelstevenstech.com/XPrepairinstall.htm