That's been the case for me too, on and off for about 24 hours now. Hopefully it's the promised upgrades/fixes so that the new site will have at least a decent fraction of the functionality of the old one.
I've been having this problem, but it doesn't seem to be a problem with the site itself, just with the first page that pops up. From the error message page, I'm able to click the Dungeons & Dragons Link, then Community, then Forums, and I get to the forums, all up and running and logged in.