I'm assuming the servers are just overloaded with the sheer voilume of people downloading. Not only do they have existing beta backers but all those of us who bought into the Horizons beta when it was available for pre-order. That's possibly a much higher volume of requests than they're prepared for.
...not that I'm commenting from the standpoint of a web performance consultant or anything...
...not that I'm commenting from the standpoint of a web performance consultant or anything...