The one you pointed to is marked as resolved, which it isn't if I'm having the same issue. So not sure why both are marked as resolved? It's all very confusing. Also the other bug report was noted as being an external IP block, which I've proved isn't my issue as I've used different alternative connections and keep getting the same error.
I am having this issue - I have contacted support, but was told to speak to you guys. It's not an external IP block as I have attempted to login with alternative connections. I think the account might be blocked. I raised a separate bug, but it was closed and I was pointed over here..
I have done some further testing and a friend logged into his account fine, from my computer, using my external IP. I can't see this being an issue with my machine after all this testing, but does seem to be an issue specifically with my account.