How to install and use the Recovery Console in Windows XP:
http://support.microsoft.com/kb/307654==
Boot into Recovery Console and log on to the current installation.
When you get to the Recovery Console prompt, type
cd \ and press "Enter".
Type
cd system~1\_resto~1 and press "Enter".
Type
dir and press "Enter".
After
you press enter you will see a list of folders (like rp1, rp2) If the
list of restore points has more than one page then press the "Enter" key until you reach the end of the listType
cd rp {number of the second to last folder in the list} and press "Enter".
Note: Example: cd rp9 if the last restore point is rp10 Type
cd snapshot and press "Enter".
Type
copy _registry_machine_system c:\windows\system32\config\system and press "Enter".
Type
copy _registry_machine_software c:\windows\system32\config\software and press "Enter".
Type
exit and press "Enter".
Your PC will reboot.
=======================If you get an access denied error when doing the above, then do the following at the recovery console:Type
cd \ and press "Enter".
Type
cd windows\system32\config and press "Enter".
Type
ren system system.bak and press "Enter".
Type
exit and press "Enter".
Your PC will reboot, go back into the Recovery Console and start from the beginning.