I have absolutely the same problem. In fact I purchased my new license this morning but I can't make it work; it says my username/password are incorrect and it even says my username is expired since 24 days.
I tried everything ! I entered my informations many many times, i supressed the Cache, I even tried to uninstall and reinstall Eset, but it still won't work !
I thought maybe I didn't have the right informations so I used the Lost license page, but the informations they sent me back were the same as this morning.
What can I do? I really need it to work, and I paid for it ...