We are running a tiny Magento store that is on v1.9.
Its been setup for a couple of months and been fine, but for some reason last week it seems to have developed an issue where orders cannot be placed. When "Place Order" is clicked at the end of the checkout the "submitting" message is shown but instead of confirming the order and redirecting to the Success page the "Place Order" button just re-appears.
No code has been changed so we're baffled.
Am sure someone that knows what they're doing will fix it in minutes.