If he doesn't need to break into the macro, make it run say every minute
by putting
 Application.Wait Now+TimeValue("00:01:00")
in the loop.

If he needs to break in, you can use Application.OnTime to run your
update macro once but it's a bit more complicated:

Dim NextTime As Date  ' at top of standard module

Sub Auto_Open()      
StartUpdate
End Sub

Sub Auto_Close()
StopUpdate
End Sub

Sub StartUpdate()
NextTime = Now + TimeValue("00:01:00")
Application.OnTime Now, "DoUpdate"
End Sub

Sub StopUpdate()
If NextTime<>0 Then
 Application.OnTime Now, "DoUpdate",Schedule:=False  
 NextTime = 0
End If
End Sub

Sub DoUpdate()
' your code to do one update of the screen
StartUpdate
End Sub

Hope this helps

Bill Manville
MVP - Microsoft Excel, Oxford, England
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