Persistent Beachball in Messages A few days ago, I was chatting via Messages and because the phone I was tethering off of went dead, and I reconnected after connecting to the wireless network of the hotel I was in, which is...dubious at best.

Now Messages isn't working. It loads, I can receive messages via notifications and the unread messages number increments, but any attempt to interact with the application directly gets caught in a beachball, and Messages shows as Not Responding in Activity Monitor, and is taking up 100% of a core. Weirdly, it's persisted past a simple OS reinstall, which is surprising.

Any idea what's going on here, or how to fix it?
You can try and remove the ~/Library/Messages and
~/Library/Caches/Messages folders, then restart.