Underlying connection was closed?

I downloaded the beta a few days ago and until now I couldnt log in due to my name and password being wrong, even though they are right.

Now, today, the login comes up with "The underlying connection was closed: An unexpected error occurred on a receive".

I have allowed the beta on my firewall as an exception etc and still cannot log in. This is getting very frustrating especially after a 4-5 hour download in the first place.