Thanks, there's a corrupted player profile. It's probably yours, but could be another player's if they connected to your p2p game.
From the Launcher/Tools/Clean game data... menu, check the boxes for Game Settings, Discovered Maps of remote games/All maps, Player profile, and serveradmin config.
Then press "Clean". After that, don't start the game; use Steam to verify the game files. After that try to start the game again.