How do I fix "Windows XP could not start because the following file is missing or corrupt"?

Apparently the file C:\windows\system32\config\system is missing from my computer. I have done nothing to make this happen.
I have tried repairing using the Windows XP installation CD, but to no avail.
Please help, there's too much stuff on my computer that I can't bear to lose :(
Update: I have been told that reinstalling Windows will wipe everything from my laptop. This really must be the the last straw for me. I need to go through all other options first.
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