Excel 2003 Error:The file (list file name) may have been changed .

We are getting this error on a handful of systems when a file is saved
(either through file save or the save icon). The error is "The file (list
file name) may have been changed by another user. If that is the case, what
do you want to do ? Save a copy or Overwright changes. There is an artcle on
this on the Microsoft web site, but it deals with Office XP not 2003. The
registry is a little different. Any ideas of how to turn this off?