Can's check out

I can add things to my cart. I can do just about everything else. When it comes time to pay however, I get led around in an endless circle. I can't get anything done. I can't recharge the reloadable cards, I can't pay for anything at all (and this is with the only card that I ever use for walmart that worked perfectly well 4 days ago on Walmart's website. They report no problems. I beg to differ. How is it I can shop all my regular sites except Walmart's? The problem is definitely not on my end.