Many times you must have seen this message:
Windows could not start because the following files is missing or corrupt
\WINDOWS\SYSTEM32\CONFIG\SYSTEM or \WINDOWS\SYSTEM32\CONFIG\SOFTWARE
Now to get rid of this error, you need to fix the files.
Follow the steps to fix the error:
1. Insert and boot from your WindowsXP CD.
2. At the first R=Repair option, press the R key
3. Press the number that corresponds to the correct location for the
installation of Windows you want to repair. Typically this will be "1"
4. Enter in the administrator password when requested
5. Type
cd \windows\system32\config
6. Depending on which section was corrupted:
ren software software.bad or
ren system system.bad
7. Depending on which section was corrupted:
copy \windows\repair\system
copy \windows\repair\software
8. Take out the CD ROM and type exit.
That's it your error is fixed now.