Pressing PLACE ORDER causes permanent freeze; new window does not help

I can shop & add items to my cart, update quantities, etc, but as soon as I press the button the place the order, it just shows that little wheel going around...FOREVER. Closing the window, even killing the process via Task Manager, and opening a new one, does not help. I sign in again, it shows me my cart & again & can do ANYTHING EXCEPT ACTUALLY COMPLETE THE ORDER. My browser is working fine on other sites. It's Walmart's cart, the complete order/place order button (whatever they call it--I can't check because that window is caught in a never-ending circle).