>Largest customer called today reporting a Not a Table error. Investigation showed total corruption of all DBFs, all high-ASCII characters when viewed in Notepad. Excel files in the directory showed similar results. In the process of restoring from backup, but we're at a loss to determine cause, and virus looms at the top of the list - anyone know any we can research?

As Naoto points out it looks like a CryptoLocker-type malware attack: http://en.wikipedia.org/wiki/CryptoLocker

It will attack all recognized user files, not just XLS/DBF etc. Some variants will also attack files on any network shares that can be accessed. Even worse, some will attack any recognized on-line backups; depending on what you use for backup it may encrypt those so you can't restore from backup.

Heads-up for lurkers: be sure to have off-line/off-site backups as a fallback position against this type of attack - and for general disaster recovery (against fire, theft etc.)