Could there be a problem with your ISP?
No, the ISP isn't the issue, I also cannot login (using IE, on Win7 64bit), which also rules out raising a support case, updates, you name it ... I thought it was a temporary glitch due to an update of their website, but it seems permanent after all this time. I'll switch browser if need be, but one shouldn't have to, especially with such a common browser. Maybe it has something to do with pop-up blockers, or virus scanners, but their website is trying to do something out-of-the-ordinary, causing a runtime error on their server. Theirs is the only website I've ever encountered this error, it's something at their end that's wrong, and there's no way to contact them without logging in, which doesn't work.