Steven Zahm@ Karine
I do not think the conflict is in the HTML markup. I think it is in the javascript. It hard to tell though because there are no console errors being shown and there is a heck of a lot of javascript … that’s why I’m guessing
Since you were able to narrow the conflict down to the jQuery Slider library used by Hours my guess is that the javascript for the theme’s header slider just happens to use the same name to init it’s header slider. Look at line 1214 in the theme’s script.js file. jQuery Slider is registered with the exact same name. Since Hours loads just about dead last it would “overwrite” the existing slider.
That guess seems to make sense now. When looking at the page prior to removing jQuery Slider, the broken header showed what looked like a button in the upper left. I’m guessing that was actually a jQuery Slider control.