Make sure that the animation button is turned off on that event page (the one with the graphic). If you have all the stuff sitting on a single event page, for example, lets say you have the animation turned on for the first graphic, stuff happens, then you change graphic and then move the event, the animation will still be on. Make a new event page and turn it off. So instead of changing the graphic, turn on a self switch and make that page of the event the new graphic instead.
If this doesn't help, then I'm not really sure why it would still be walking.
Oh, or you could just turn off the animation via the movement event command. I think it's one of the options in there - if not, then make a new page like i just said.