I'm currently having the same problem that A_T_R is dealing with. I was talking to one of my friend named Maple Syrup days before and he had this problem as well. Whenever I tried to join my server and pick a team, it would crash. My game would freeze and have a connection message. Looking at my Tf2 server manager the server would automatically shutdown. I updated sourcemod, metamod, and freakfortressbat to the latest versions and I would still have this problem. I am using the server with wine but that was never a problem before up until now.
I have
this video to show the problem
Edit: I even tried to make a clean ff2 server without any plugins, just the latest versions of what i mentioned above. I could only play the beginning pvp round before the server crashed and shutdown when the boss round happened.