If you are in MSDOS, at the C:\Windows prompt type
Attrib -s -r -h C:\Windows\System.dat (press Enter)
Attrib -s -r -h C:\Windows\User.dat (press Enter)
To make the backup copies type:
copy C:\Windows\System.dat C:\Windows\System.000 (press Enter)
copy C:\Windows\User.dat C:\Windows\user.000 (press Enter)
To Restore the Registry
copy C:\Windows\System.000 C:\Windows\System.dat (press Enter)
copy C:\Windows\User.000 C:\Windows\user.dat (press Enter)