The C000218 error is a registry error that may prevent your Windows XP operating system from working correctly. In some cases, it causes the blue screen error message (also known as the Blue Screen of Death) to appear, preventing the operating system from working at all. Under normal circumstances, you'll need to have a professional fix your computer, but there is one method you can try before taking that step. It involves running the Recovery Console and using "chkdsk" to attempt to repair the damaged sectors.
Type "chkdsk C: /R" in the Command Prompt, and hit the "Enter" key.