Help needed please Jscrollpane issue

Hi people,

I am having 1 problem with Jscrollpane, please navigate to the site here
www.ngmmodels.co.uk

The central div contains all the models, now there should appear a scroll bar on this div, if it doesn’t appear at first try navigating to the women, men or new faces sections, or even refresh and the scroll bar will appear. It is behaving very strange, sometimes it is visible and other times not.

Please any suggestions would be VERY helpful, I have tried for a couple hours figure this out and have decided I need some help with this.

Joe