If you have just entered your payment details and suddenly the transaction page has not loaded, this could very well mean that the 3D Secure verification has failed.
This can happen due to a variety of reasons:
- You currently have a pop-up blocker installed which is restricting the additional 3D Secure page from opening. Disable the pop-up blocker for a few minutes and then you will be able to complete your payment
- Unusual location or new device
- Your card provider may have be experiencing an issue or may not support 3D Secure authentication, as a first step contact your card issuer to find out.