Summary
Certain documents may become corrupted when stored on a Windows 2000 computer that is using NTFS file system compression.
Cause
The original release of Microsoft security update 920958 (MS06-049), dated August 8, 2006, contained the possibility of corrupting compressed files that are larger than 4 kilobytes (KB).
Resolution
Microsoft re-released a fixed version of security update 920958 (MS06-049) on September 26, 2006. Install this updated version of the security update.
Note: The updated version of the security update corrects the issue. However, it does not restore any files that have already been corrupted.
Please see the following Microsoft Knowledge Base articles for more detailed information