My boss was editing a workbook via her VPN connection. Another user (not
using the VPN) was able to open the worksheet, edit it, and save it. I'll let
you imagine who's being blamed. I think that I've seen this before, has
anyone else? Does anyone know why it happens? Can anyone recommend a way to
prevent this?

The workbook is on a shared drive on a Windows server. My boss and the other
user are using Windows XP with Office XP or 2003. The workbook is *not* set
up to be shared.

Thanks.