I get a prompt from Excel that I never used to get when saving files. When I
try to save an Excel file, I get the following prompt:

The file 'filename.xls' may have been changed by another user since you last
saved it. In that case, what do you want to do?

My options are to Save a copy, or Overwrite changes. This started happening
about a month ago and the only significant changes that I've made to my
system that might cause this would be a Windows XP update. I have a home
network with a shared network drive (Buffalo Linkstation) and I notice that I
only get this prompt when opening the file from my Linkstation HDD, not when
opened from local drive. No one else is on my network when this happens so
it can't be that someone actually has the file opened at the same time as me.
Doesn't happen with other Office 2003 programs. Not a big deal but I'd like
to turn it off - any ideas?