Use this page as an example:
If you log in as a pre-existing user and scroll to the bottom you will note that you are not able to deselect the radio button for "Use Saved Payment Information."
Looks like there's an onClick in place on that radio button that is not firing correctly. When clicked the classes .li_cc_number, .li_cc_cvv2, and .li_cc_exp_month have their styles appear to change but they remain set to display:none; and the radio button remains selected.
This is a subscription checkout for a v0.5.0 store.