Hello brentjohn,

I forgot when using the Workbook Open event that you must use fully qualified constructs. Replace your code with the code below. It should take care of the problem.

Private Sub Workbook_Open()
    If (Application.CommandBars("Ribbon").Controls(1).Height > 100) Then
        Application.CommandBars.ExecuteMso "MinimizeRibbon"
    End If
End Sub

Private Sub Workbook_Deactivate()
    If (Application.CommandBars("Ribbon").Controls(1).Height < 100) Then
        Application.CommandBars.ExecuteMso "MinimizeRibbon"
    End If
End Sub