Restore Windows XP to a Previous Point
Step 1

Insert the original Windows XP CD into the CD-ROM drive and then restart the computer. Press "Enter" when prompted to boot from the Windows XP CD.
Step 2

Press "R" to go to the Recovery Console and select option "1" for the Windows installation. Then press the "Enter" key.
Step 3

Enter the administrator password.
Step 4

Type "cd system32\config" at the command prompt.
Step 5

Type "ren system system.bak" at the "C:\system32\config" prompt.
Step 6

Type "cd \" and press "Enter." This returns you to the root directory of the C: drive.
Step 7

Type "cd system~1" and then press "Enter." If you encounter an "Access Denied" error, type "exit" and reboot the computer. When you return to the command prompt, type "cd system~1" again.
Step 8

Type "cd_resto~1" and "Enter." Then type "dir" and "Enter" at cd_resto~1 prompt.
Step 9

Type "dir" and press "Enter." This brings up a list of files in the directory. Locate the file named "rpX" where X is the highest number and latest restore point. Type "cd rpX" at the command prompt and then press "Enter."
Step 10

Type "cd snapshot" and then press "Enter."
Step 11

Type "copy _registry_machine_system C:\Windows\system32\config\system" and then press "Enter." Then type "exit" and allow the computer to reboot. A successful reboot into Windows XP indicates there was an issue with the system file.