Are you by any chance shooting in Aperture priority mode? Konika Hexar (non-RF version) has the highest
shutter speed of 250. With this film in bright daylight you must use aperture 16 or smaller. I see one of your shots has rather shallow DOF which leads me to think that you opened the lens too much and exceeded the maximum shutter speed on this camera. For daylight outside shooting, I would recommend switching to ISO 100 film, and watch your shutter speed/aperture carefully.
EDIT: Of couse, there is always the possibility of shutter sticking in an older camera.