I have a problem.

I have an Excel 2003 workbook on a network that is constantly being accessed
by different people. It's a master copy that's supposed to have its changes
saved every time someone's done with it, but the problem is that it doesn't.
Someone goes in, makes their changes, saves, quits out, and then a few hours
later they come back and the changes haven't been saved. Strangely enough,
I've had people go back an hour later and the changes are there, but then a
little later, say in four hours, the changes are gone.

I've asked around and it seems like everybody who's been using the workbook
is having the same problem. It's very important that everyone's changes are
kept. Can anyone help out?

Thanks.