What bench is that? There must be something that collides inside the clothing. Maybe it was imported wrongly in Poser. Did you saved and reload it or starting it from scratch every time? What I also would try is to load the bench obj file in a modeler to see if there are not some polygons that would collide with the clothing in that area. Maybe one is already enough to do this but, in this case, it would mean that Poser 13 was improved in collision or that the subd level of the bench was changed.