Option Explicit
Sub Auto_Open()
Msgbox "Remember to save as a new name. Well, if you want!"
End Sub

or

Option Explicit
Sub Auto_Open()
Application.Dialogs(xlDialogSaveAs).Show
End Sub

To just show the File|SaveAs Dialog

wrvadmin wrote:

I need help in creating a macro that will prompt the user who opens the
workbook to automatically save the workbook with a new file name. I have a
workbook that is revised on a daily basis and I want to maintain the previous
day's file. I am generally the one who opens the workbook, but there will be
days when someone else opens it on their computer. It doesn't have to be a
mandatory save, but I want the prompt there as a reminder to save with a new
filename.

--

Dave Peterson