hmm, I did as you said, but this is obvious Amazon problem. I get message to late, about 30 minutes later, and that code which I get after 30 min is not valid :)
didn't quite understand you. I have same problem. Amazon doesn't recognize my mail or password (I get that in the message when I try to register kindle app).
Did you press FORGOT YOUR PASSWORD? and then you got a code in mail or something else?
I had that problem on my laptop, and it was very annoying. Tried everything and only thing which helped me was to reinstall wifi adapter driver. It solved problem, but after every new windows update I have to do it again.