Countless Windows 2000 Professional and Server users are reporting that Windows Update KB920958 is causing permanent loss of data if the “compress” attibute is set for folders.

This is effecting new files which are close to a mutiple of 4k in size will have the last 4,000 bytes or so overwritten with 0xDF (a sharp “S” in German, which looks like this: ß ). It has been confirmed that by either uninstalling the KB920958 update or turning off the compression attibute it will prevent further loss of data.

Microsoft are yet to say anything offical about this issue.