I had the error “The game has shut down because of broken IPF files” so I used window mode and cancel trick to logged in. It was okay if i just move around. But if i attack monster in 30 second i will be kicked out from game, then a pop up similar to “Disconnect from server, you will be moved to character selection” appeared and then “The game has shut down because of broken IPF files” => out game.
“Verify Integrity of Game Cache” method didn’t work for me.
Happens to me too, but not during sustained auto-attack. It sounds like an issue with high ping/too much ping spikes.