windows\system32\config\system file missing or corrup

See the following from ElderK (or wait until he shows up in person).  Because I don't know if your old Dell can boot from USB -- but probably does have a CD drive -- I've given you his directions for creating a bootable CD.

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For that message, you always, always, always need to start with a chkdsk with error correction first - that will usually fix things up.  After that you may want to undo your registry restores...

Here's how:

Make yourself a Hiren's Boot CD which you can download from here:

http://www.hirensbootcd.org/download/

The ZIP file is large, so the download will probably take a little while to complete bit it is worth it.  Then unzip the download to extract the Hirens.BootCD.ISO file that will be used to create your new bootable CD.

Creating a bootable CD from a .ISO file is not the same as just copying the .ISO file to a blank CD.  You have to use software that understands how to burn a .ISO file to a CD to create a bootable CD.

In the Hiren's ZIP file are the BurnToCD.cmd file that you can double click to launch it, but I have never used it and prefer to use ImgBurn.

If you need a free and easy CD burning software package, here is a popular free program:

http://www.imgburn.com/

Like many third party programs you might install, the ImgBurn installation defaults to installing things you probably don't want installed on your system in the form of extra Internet browser toolbars or may make other adjustments to your browser.  You don't want to install any of that so you have to pay attention during the installation.

When clicking through the installation screens be sure to pay attention to the screens and always choose a Custom install and UNcheck the following (or any other things like it):

UNcheck:

Install the AVG toolbar and set AVG Secure Search as my default search provider

Set AVG Secure Search as my homepage and newly opened tabs

Choose custom installation again and UNcheck the following:

Uncheck:

Install QuickShare

There could be other things too.

Here are some instructions for ImgBurn:

http://forum.imgburn.com/index.php?showtopic=61

It would be a good idea to test your new bootable CD on a computer that is working.

You may need to adjust the computer BIOS settings to use the CD ROM drive as the first boot device instead of the hard disk. 

These adjustments are  made before Windows tries to load.  If you miss it, you will have to reboot the system again.

When booting on the Hiren's CD you will see a menu of options.  Choose the Mini XP option.  Then it will appear that Windows is being loaded and you will be presented with a desktop that has the look and feel of the Windows Explorer interface you are already used to using.

Remember:  You did not boot on your hard disk - you booted into the Hiren's desktop.

One way to check the disk for errors is to open My Computer and right click your afflicted drive and choose Properties, Tools, Error-checking, Check Now... put a check mark in both the boxes and then Start.

Sometimes that doesn't work, so you can also click Start, Run and in the box enter:

cmd

Click OK to open a Command Prompt window and enter the following command (assuming XP is installed on your C drive)

chkdsk  c:  /r

This disk checking can take a long time (perhaps several to many hours) depending on the size of the volume, the amount of data on the volume and what the disk checking finds to do.

Let chkdsk finish and correct any problems it might find. 

Depending on the the speed of your system, the size of the volume, the amount of data on the volume and what chkdsk finds to do, it may take a long time for chkdsk with error correction to complete (several to many hours) or it may appear to be 'stuck'.  Be patient.  If the HDD light is still flashing, chkdsk is doing something so don't interrupt it.  It will finish eventually one way or the other.  Keep an eye on the percentage amount to be sure it is still making progress.  It may even appear to go backwards sometimes.

You may have to run the chkdsk  /r  it more than once.

When the chkdsk runs clean, remove the CD and restart your system.

Yes - for that error, you should always start with a chkdsk with error correction (chkdsk  /r) but you are going to have to boot on something in order to do that and that something is a Hiren's Boot CD or Hiren's Bootable USB.  From a working system you can create whichever you need and you will be glad you did.

Since you have a Dell computer, what is the Service Tag Number?

It is extremely unlikely that the file is really missing or corrupt.  The problem is usually that XP just can't find the file due to some corruption in the NT File System (NTFS).  The NTFS can can get corrupted from things like a power interruption, plug pulling, using the power/reset button, aborted restart, ungraceful shutdown, etc.

Was the issue preceded by a power interruption, aborted restart, or improper shutdown?  (this includes plug pulling, power buttons, removing the battery, etc.)?

Depending on youre xp installation resources (xp install cd,or xp on a partition),

go to run,type: cmd  In cmd,type: Sfc /Scannow

On a xp retail installation,one would insert the xp cd,exit the menu,Sfc,runs

auto.Repairing/or Replacing windows files,with dell,it'll ask,or run auto.

Either way,once thru,type: CHKDSK C: /F  agree to restart,type: EXIT

restart pc