When you encounter problems so severe that you believe you’re missing important system files, you can run System File Checker to repair those missing files. Often, this works to resolve the problem. You’ll know you’re missing system files if cryptic, alien error messages begin to appear, usually at bootup.
To run System File Checker:
1. Choose Start | All Programs | Accessories | Command Prompt.
2. Right-click Command Prompt and click Run as Administrator.
3. Type sfc /scannow.
4. Wait while the scan completes.
5. Restart the computer when System File Checker completes, if errors are found and resolved, even if you are not prompted to do so.
If you still see missing-file errors or your computer ...