I cannot start Windows on my PC! I get an error message reading:

"Windows cannot start because "C:\WINDOWS\System32\config." is corrupted or missing. Insert original Setup CD-Rom and press ‘r’ at setup to begin repair."

I have looked at the software that I recieved when I got my computer (it was given to me by my neighbor two years ago), and I cannot find the original Setup CD-ROM, and I can’t get the others to run at all. I have gone to dell’s support website on another computer and tried their suggestions, which did not work. I tried the command-line string, but I can’t input anything. I’ve tried looking on here for solutions, and attempted what I found, but nothing’s worked so far.

Please help, it was working perfectly fine on Thursday evening, but on Friday, this problem began. I do not know what is causing it. To be able to get the best help, here are the details of my operating system:

Manufacturer: Dell
Edition: Windows Media Center Edition
Software Package: Microsoft Office Windows XP 2000
Year Manufactured (guesstimate): 2001
Virus/Malware/Spyware Protection Software: Avast!, Super AntiSpyware, Spybot: Search & Destroy, Ad-Aware.

I need to resolve this quickly, please. Any suggestions you may have will be tried, and are *very* welcome! Thank you very much to anyone who can help me!