With this code in a macro for Excel XP in VBA, I open an 'output' document
and then it in turn opens a source document so that the cells can update. I
want to hide the source document when it opens, but leave all other Excel
files, especially the one I just opened, unhidden. Sometimes this works and
sometimes it doesn't. Could anyone tell me why, or tell me if there is a
better code to make sure I am just hiding the source document?

The code in "This Workbook" object of the 'output':

' Code Purpose: When opening output (slave) document, open main to update
the cells correctly.
Private Sub Workbook_Open()

Dim wb As Workbook
On Error Resume Next
Set wb = Workbooks("Workbook.xls")
If Not wb Is Nothing Then Exit Sub
On Error GoTo 0
' Freeze screen, no screen flickering during the running of the macro.
Application.ScreenUpdating = False
'Opening the main document:
Workbooks.Open "Workbook.xls"
'Hiding the main document:
ActiveWindow.Visible = False
Application.ScreenUpdating = True
End Sub

Thanks a lot!
--
AnthonyJ