Many of the USD's preferences are updated or refreshed by Pro Tools at launch. The NTSC/PAL setting is not one of those, thus it is possible for the setting to get reset. To fix: take the USD out of remote mode by either quitting Pro Tools or by depressing Clock Reference, Positional Reference, and Frame Rate on the USD's front panel simultaneously.Hit Set and toggle the Up button until the "Video Sy" screen is reached. Hit Set again and use the Up or Down button to toggle to the desired setting (NTSC or PAL).If the USD seems to lose this setting frequently, contact Digidesign Technical Support.