my Samsung Galaxy Note 4 has taken to crashing the phone so hard when I try to load Snapchat (and this is the only app that does it) that holding the power butt

my Samsung Galaxy Note 4 has taken to crashing the phone so hard when I try to load Snapchat (and this is the only app that does it) that holding the power button down for a minute has no effect. To restart the phone I need to have usb power into it. Why Snapchat? and why only when loading my friends stories, which is the only reason I would open it.