Ok, that is the link I have bookmarked in my browser weeks ago. I tried it again now from above, I typed the correct username and password (although my Mozilla memorised those so it can't be that mistake). Still the same message: this account does not exist.
I try it in Opera and I get the same message about banned IP and inexistent account.
My account worked fine until this morning and I was on positive cash if it matters. And I haven't done anything but the usual stuff I do for weeks.
I don't think it's a browser problem since starting this morning I couldn't play from 2 different PCs on 2 different IPs and 2 different links.
I am out of ideas now.....