Firefox 4 and Banco Santander Don't Mix

Having been downloaded more than 24 million times and counting since its official release March 22, it's safe to say Firefox 4 is a popular browser. But popular or not, some Banco Santander customers are reportedly having trouble accessing their online banking services with the new browser.

The Register reported on the issue after some of its readers called in to ask about an error message saying online banking was unavailable:

A spokesperson from Santander Cards said: "We are aware that some customers using the latest version of the browser Firefox, version 4, may currently be experiencing difficulties accessing their account details online. We are in the process of rectifying this and would advise customers in the meantime to use a previous version of Firefox or Internet Explorer.

"This will not impact customers' online security. Customers who are concerned can contact us by telephoning the number on the back of their card."

Based in the eponymous Spanish city, Santander is the largest European bank with $1.62 trillion in assets.