Before doing a clean install I would try to repair XP as a first step.
Go to
http://support.microsoft.com/kb/315341/
Then scroll down to
Method 2: Reinstall Windows XP by starting your computer from the Windows XP
CD
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Since you cannot boot and presumably do not have immediate access to another
computer, here are the steps.
During boot press the function key that puts you in Setup - typically F2.
Once you are in BIOS Setup change the boot sequence so that you boot first
from CD and then from your hard drive. Exit Setup saving these changes -
with your XP Installation CD installed.
At the first screen (when booting from your XP CD) press Enter - do not
press R.
On the next screen press the default (I seem to recall it is NEXT).
Now you should shortly see a screen where your installation is highlighted
and the options are displayed.
Press R to repair the installation.
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Additionally, here is a cut & paste from the aforementioned..
http://support.microsoft.com/kb/315341/
Method 2: Reinstall Windows XP by starting your computer from the Windows XP
CD
To reinstall Windows XP by starting your computer from the Windows XP CD,
follow these steps: 1. Insert the Windows XP CD into your computer's CD-ROM
or DVD-ROM drive, and then restart your computer.
2. When the "Press any key to boot from CD" message appears on the
screen, press a key to start your computer from the Windows XP CD.
Note Your computer must be configured to start from the CD-ROM or
DVD-ROM drive. For more information about how to configure your computer to
start from the CD-ROM or DVD-ROM drive, see your computer's documentation or
contact your computer manufacturer.
3. You receive the following message on the Welcome to Setup screen
that appears:
This portion of the Setup program prepares Microsoft Windows XP to run
on your computer:
To setup Windows XP now, press ENTER.
To repair a Windows XP installation using Recovery Console, press R.
To quit Setup without installing Windows XP, press F3.
Press ENTER to set up Windows XP.
4. On the Windows XP Licensing Agreement screen, press F8 to agree to
the license agreement.
5. Make sure that your current installation of Windows XP is selected
in the box, and then press R to repair Windows XP.
6. Follow the instructions that appear on the screen to reinstall
Windows XP. After you repair Windows XP, you may have to reactivate your
copy of Windows XP.
For additional information, click the following article number to view
the article in the Microsoft Knowledge Base:
310064 How to troubleshoot Windows XP Setup problems when you upgrade
from Windows 98 or Windows Millennium Edition
After you perform an in-place upgrade
After you perform an in-place upgrade or repair installation, you must
reinstall all updates to Windows. To reinstall Windows updates, visit the
following Microsoft Web site:
http://windowsupdate.microsoft.com
For additional information about how to troubleshoot specific Windows XP
Setup issues, click the following article numbers to view the articles in
the Microsoft Knowledge Base:
312369 You may lose data or program settings after reinstalling, repairing,
or upgrading Windows XP
312368 Data loss may occur after reinstalling, repairing, or upgrading
Windows XP
For additional information about the Windows XP Setup program, click the
following article numbers to view the articles in the Microsoft Knowledge
Base:
286463 Release Notes for Windows XP Setup contained in the Pro.txt file
306824 Release Notes for Windows XP Setup contained in the Home.txt file
286647 Windows XP Read1st.txt file contents
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Keep us posted.
