To sum it up briefly:
Basically, we make use of a service provided by Gigya to help manage our userbase and customize user experiences. They recently came under a service attack when their DNS servers were redirected to one held by the S.E.A., resulting in that page being shown. Neither Gigya's servers or any information was compromised, and it is unlikely your computer was put at risk. For more detailed information, you can refer to the statement released by Gigya on their blog: http://blog.gigya.com/regarding-todays-service-attack/