Windows could not start because the following files is missing or corrupt

I Had this old chestnut appear at a clients the other day.

“Windows could not start because the following files is missing or corrupt
\WINDOWS\SYSTEM32\CONFIG\SYSTEM or \WINDOWS\SYSTEM32\CONFIG\SOFTWARE”

 or

\WINDOWS\SYSTEM32\CONFIG\SYSTEM or \WINDOWS\SYSTEM32\CONFIG\SYSTEM”

I remembered this easy fix. 

Step 1 : Insert and boot from your Windows XP CD

Step 2 : At the first R=Repair option, press the R key

Step 3 : Press the number that corresponds to the correct location for the installation of Windows you want to repair. Typically this will be #1

Step 4 : Enter in the administrator password when requested

Step 5 : cd \windows\system32\config

Step 6 : Depending on which section was corrupted:
ren software software.bak or ren system system.bak

Step 7 : Depending on which section was corrupted
copy \windows\repair\system
copy \windows\repair\software

Step 8 : Take out the CD ROM and type exit