Sam, you'll probably begin to do the same as me now, which is never allowing vba to run until I've had a look at the code behind the workbook.
I suspect the command you're looking for might be:
Application.DisplayFullScreen = False
although when I set this property to True on mine I can still see the top right windows state buttons!
The entirety of the code in the workbook is:
Private Sub Workbook_Open()
Application.DisplayFullScreen = True
Sheets("Summary").Select
End Sub
Private Sub Workbook_Close()
Application.DisplayFullScreen = False
End Sub
The last one never gets called because it's not an event, it would do better if were n a Private Sub Workbook_BeforeClose(Cancel As Boolean)