Seems that you'll have to do a system restore.
Boot the computer using the XP CD. You may need to change the boot order in
the system BIOS so the CD boots before the hard drive. Check your system
documentation for steps to access the BIOS and change the boot order.
When you see the "Welcome To Setup" screen, you will see the options below
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 start the Windows Setup. Do not choose "To repair a Windows
XP installation using the Recovery Console, press R", (you Do Not want to
load Recovery Console). I repeat, do not choose "To repair a Windows XP
installation using the Recovery Console, press R".
Accept the License Agreement and Windows will search for existing Windows
installations.
Select the XP installation you want to repair from the list and press R to
start the repair. If Repair is not one of the options, END setup. After the
reboot read
Setup will copy the necessary files to the hard drive and reboot. Do not
press any key to boot from CD when the message appears. Setup will continue
as if it were doing a clean install, but your applications and settings will
remain intact.