I think this is because it only gives you the option in the settings to calibrate (set screen parameters) 1280x720@50hz, if you are playing a file at 1080p24hz (which will only play at 50hz on the VU+) in normal xbmc you would have to set the parameters for that ratio, this you would do by pressing ok button going to video propertys and setting your blue bars (this has to be done for every screen size and frame rate file) unfortunatly i dont think the VU+ lets you do this because it uses its own player and not the xbmc interface.