My guess would be you have a conflict using the jquery somewhere within your site. You might want to look at your plugins and see which ones are using jquery.
Also, you may want to disable your plugins, one at a time, and see if you can find out which one is interfering with the slider.
NOTE: You also have a few other “weird” things going on…
1. You are getting some CSS displayed on your page from the Halloween Souvenirs post.
2. Your top right widget area is overlapped. This might be the result of not closing a
<div> tag properly.