Another issue, I introduced the site to a coworker, and he successfully registered an account, but then when he tried to login, the site just told him "no such user". He said he also experienced the same thing when he tried again at home, using a different ip, browser and bitcoin address. I also just tried creating another account myself using a different address and experienced the same problem.
I guess you are trying to login with your Bitcoin address. You must use your username if you are registered.
Bitcoin address login is for the unregistered users.