I've played Dominion on this laptop several times before, but not for a few weeks. It's a Windows machine - quite a high spec Lenovo Legion, several orders of magnitude more powerful than the old laptop which runs Dominion okay (if a bit inconsistently due to general decrepitude). One other quirk that's occurred with this machine is that the cards in my hand are sometimes blank - just the card outline shows - until I click on them or something.
One other thing I've just tried is a hard reset (60 seconds plus on the power button), which has solved browsing-related problems in the past, but it's had no effect here, still getting the spinning castle.