Cart does not function in Internet Explorer 11

Hi,

I really don't think this is a browser issue. I am attaching three screenshots to show the cart problem. The cart works fine from the front page; however, if you go to an individual product page and add a product to the cart, it will show up on the sidebar. However, if you look at the top cart, it shows 0 products. Then, if you click on Show Cart, you will see the product in the cart, but still the "0" products in the cart. THEN, when you click on Checkout, everything swaps places and the top will show "1" item in the Cart, but the page shows "the cart is empty."

Please look at the screenshots and let me know what you think (there is not an area to add images from inside the dashboard, so I will go back and edit once this is posted). Yes, client is using IE11, but the cart should work in any browser, right?

Thanks,

Beverly

p.s. I posted this under the other site that is also not working properly, but this is the site that is urgent. The client now has HIS clients calling me to tell me they cannot place an order. I have also had another web developer in the area test on their computer, and they get the same disfunction. Thank you.