At the Command prompt type the following, pressing Enter after you have typed each line. In this instance i don't think there is any other choice but to try get hold of the CD. This folder is unavailable and appears dimmed because it is set as a super-hidden folder. I am fed up of this problem. http://upxpress.net/windows-system32/windows-system32-config-system-is-missing-or-corrupt.php
If all goes to plan, you've just fixed your computer Without needing the Windows XP CD! This worked perfectly :))))
Big thanks from france !