We have a Magento website that a customer cannot proceed to checkout in IE11. It hits the one step checkout page, and redirects back to the shopping cart. The contents are still in the cart. The ssl is valid and working. Works in IE11 on other computers, along with Firefox, Chrome, and Safari.
Cleared cache, cleared browser cookies, did a complete IE11 restore. Flushed their DNS. Still same thing, when they hit proceed to checkout on the shopping cart page it redirects back to the cart.