Ok, I think this happened when someone tried to join. I may have been alt-tabbed.
-----------------------------------Application_ThreadException-----------------------------------System.ArgumentException: An item with the same key has already been added.
at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
at Lidgren.Network.NetServer.AddConnection(Double now, NetConnection conn) in C:\vcother\lidgren-network\2009-7-07\lidgren-network\Lidgren.Network\NetServer.cs:line 329
at Lidgren.Network.NetConnection.Approve(Byte[] localHailData) in C:\vcother\lidgren-network\2009-7-07\lidgren-network\Lidgren.Network\NetConnection.Approval.cs:line 36
at Lidgren.Network.NetConnection.Approve() in C:\vcother\lidgren-network\2009-7-07\lidgren-network\Lidgren.Network\NetConnection.Approval.cs:line 14
at AIWar.NetworkServerWrapper.CheckServer() in C:\vcprojs\AIWar\DX\NetworkServerWrapper.cs:line 147
at AIWar.GameForm.RunNextCycle(Boolean DoRendering, Boolean DoScrollingAndInput) in C:\vcprojs\AIWar\GameFormParts\GameLoop.cs:line 535
at AIWar.GameForm.gameLoop() in C:\vcprojs\AIWar\GameFormParts\GameLoop.cs:line 220
at AIWar.GameForm.GameForm_Load(Object sender, EventArgs e) in C:\vcprojs\AIWar\GameFormParts\Startup.cs:line 253
at System.Windows.Forms.Form.OnLoad(EventArgs e)
at System.Windows.Forms.Form.OnCreateControl()
at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
at System.Windows.Forms.Control.CreateControl()
at System.Windows.Forms.Control.WmShowWindow(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.ContainerControl.WndProc(Message& m)
at System.Windows.Forms.Form.WmShowWindow(Message& m)
at System.Windows.Forms.Form.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)