Hi, I'm on a MacBook, up to date.
For well over a month, I've had issues with Arena. It usually happens when I go to open a pack, but sometimes it happens at other random times. What usually happens is the screen will flicker abnormally, but the main graphics (like a pack of cards opening up) will stay frozen, but the audio will play as usual. Sometimes the graphics will be missing on parts of the screen. Usually there's also decent amount of lag.