If the Windows 2000 Synchronization Wizard suspects corruption in the Client Side Caching, the subject message may be displayed.

The %SystemRoot%\CSC folder hold the offline files. This folder is hidden, and should never be manually altered or it will completely destroy the functionality of Client Side Caching. 

When corruption of the CSC is suspected:

1. Open My Computer.

2. Press Folder Options on the Tools menu.

3. Select the Offline Files tab.

4. Hold down CTRL+SHIFT while pressing Delete Files.

5. Press Yes when prompted with:

The Offline Files cache on the local computer will be re-initialized. Any changes that have not been synchronized with computers on the network will be lost. Any files or folders made available offline will no longer be available offline. A computer restart is required.

Do you wish to re-initialize the cache?

6. Press Yes to restart Windows 2000.