Preparing to launch we have seen this problem for the past few months of development. When you first come to the page, the slider sticks on the first image. Sometimes it happens for a second or two, sometimes longer.
At this moment it is hanging and not starting while the "ad boxes" are trying to load, likely while it is remotely calling images from smugmug. A problem with that service not your theme. (I think) However, that tells me that I may be able to make some change to the slider to be sure it loads first, and does not wait for the other items on the page.
When I hit "X" (stop) everything loads when we are in this locked condition.
The site is http://VisitLondonderry.com to see the problem
We did make a change to the slider code assisted by Dude to point to specific pages not to posts http://www.kriesi.at/support/topic/featured-slider-pages#post-19852
I do not think we have any other changes to index.php