It happens from time to time. Could just be a lot of traffic or a ddos attack. I'm sure a lot of people are trying to access the forum with the current price climbs as well so that could have something to do with it.
This has happened before, and theymos has solved it. Probably about bandwitch issues and matters relating to the number of online users of this forum. Hopefully can be smooth again because this is quite disturbing, we are quite difficult though to access a post. I believe in existing team doing bitcointalk development forum. It may take some time to fix it.
I remember that when someone is attacking this forum and I am so pissed in my ISP because I thought that is just my internet connection.
I think I know why we can't access the forum, they added a captcha when you are logging in here in the forum. It is my first time seeing that here in the forum. I don't know why though, I think it is not that big deal, luckily it is not a DDos attack now.