Do the following:
1) Open a private (Firefox) or incognito (Chrome) window.
2) Navigate to "dominion.games".
3) Enter your name and password, but do not click on the Login button.
4) Instead, below that button in smaller print is text "Kick and Resign". Click on that text. It should clear up problems, now you can play on "dominion.games" in a normal window again.