That pawn figure shouldn't be visible in the game. You probably have a bug in one of your mutators. I remember a bug in ATB that allowed spectators to join a team as a player, causing exactly this. Although I don't think it is responsible for disconnects, having a player running around not as an ordinary playerpawn can really mess up your game. In CTF for example, such a player can take the flag and there's no way to get it back, since no damage can be inflicted on this type of player.
This also seems to be the case on your server. "Hero" can clearly be seen being a spectator (white text in chat), yet he also appears in the game as a pawn. Now it's up to you to find the cause. Perhaps a list of all the mutators you have installed on your server could help. Or you could do some trial and error: start removing mutators one by one until this problem no longer manifests itself. All things said and done, I don't think this is an involuntary act. So try chatting up to this "Hero" and ask him how he did it.
It also appears to be a bug in (perhaps older versions?) of UT. I
quote: "This is caused by spectators going into certain zones in a map where they can get killed. When they respawn, they are a chess pawn. They can grab the flag, relics, weapons, etc...". So make sure you run v451. If nothing else, you're all patched up
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