Yes, that would explain it.
After updating to the latest set of MaxGUI drivers, you will need to delete the old module folders from BlitzMax\mod\brl.mod for BRL.CocoaMaxGUI, BRL.FLTKMaxGUI, BRL.MaxGUI and BRL.Win32MaxGUI.
After updating to the latest set of MaxGUI drivers, you will need to delete the old module folders from BlitzMax\mod\brl.mod for BRL.CocoaMaxGUI, BRL.FLTKMaxGUI, BRL.MaxGUI and BRL.Win32MaxGUI.