Private Sub Workbook_Open()
Dim ws As Worksheet
For Each ws In Worksheets
If ws.Name <> "INTRO" Then ws.Visible = xlSheetVisible
Next ws
' Hide INTRO sheet
Set ws = Sheets("INTRO")
ws.Visible = xlSheetHidden
End Sub
Private Sub Workbook_BeforeClose(Cancel As Boolean)
Dim ws As Worksheet
' Unhide INTRO sheet first
Set ws = Sheets("INTRO")
ws.Visible = xlSheetVisible
For Each ws In Worksheets
If ws.Name <> "INTRO" Then ws.Visible = xlSheetHidden
Next ws
End Sub