When you run SFC (System File Checker), you receive:

   Windows File Protection                                 Files that are required for Windows to run properly must be copied to the DLL cache.                                 Insert your Windows 2000 Server CD-ROM now.
When you mount the CD-ROM, you receive:
   Windows File Protection                                 The CD you provided is the wrong CD.                                 Please insert the Windows 2000  CD-ROM into your CD-ROM drive.
If you have the computer security policy set to Restrict CD-ROM access to locally logged-on user only, you need to disable this policy to run SFC, because Windows File Protection is controlled by Winlogon which can not use the CD-ROM while the policy is enabled.

You can temporarily disable the policy:

1. Use Start / Run to execute MMC (press OK).

2. Use the Console menu to Add/Remove Snap-in...

3. Using Add on the Standalone tab, Press Group Policy in the Available Standalone Snap-ins list.

4. Press Add, Finish, Close, and OK.

5. Navigate to Local Computer Policy\Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options.

6. Double-click Restrict CD-ROM access to locally logged-on user only and press Disabled and OK.

7. Press Console / Exit and restart your computer.

8. After SFC finishes, you can Enable the policy.