I just ran across the same issue, actually. I went into the Portfolio Slideshow >> Settings tab and unchecked the box next to jQuery cycle (at the bottom) and that seemed to fix it! I think the issue, at least for me, was that IE loaded two instances of jQuery cycle and broke the slideshow.
I looked at the code on your site, and it appears you also have jQuery cycle loaded twice… so I think you can solve it by taking the steps I did.
