I'm getting this error as well, very frustrating. I've emailed the customer service email for help yesterday but not heard anything yet (not sure of their response time).
Did you manage to sort the problem? If so I'd love to know how as my hubby who is very technology savvy is struggling to help me with this issue.
A delay in response right now could very well be the timing - It's Thanksgiving Day here in the US which is a holiday and I strongly doubt that there is anybody working there now.
I am registered and I have no problem accessing the site. I don't remember when I did the registration but it has been several years.
Since there are quite a few tagged as "recent", it doesn't look to be down.
I sent an email to customer support in May (a couple of days before I posted this) and I still haven't gotten an answer. I don't think Thanksgiving is the problem.