server keeps crashing when joining

So... Only Found this:

12.03 12:47:20 [Multicraft] Huntondoom ran command Message of the Day
12.03 12:47:20 [Connect] User Huntondoom, IP xx.xx.xx.xx

and this is the error outputting to my client: http://imgur.com/op6HTOU

But when I shut down the server this error appears:
12.03 13:37:46 [Server] INFO Saving chunks for level 'LegendofKorra'/The End
12.03 13:37:46 [Server] INFO Saving chunks for level 'LegendofKorra'/Nether
12.03 13:37:46 [Server] INFO Closing listening thread
12.03 13:37:46 [Server] INFO at if.run(SourceFile:61)
12.03 13:37:46 [Server] INFO at java.net.ServerSocket.accept(Unknown Source)
12.03 13:37:46 [Server] INFO at java.net.ServerSocket.implAccept(Unknown Source)
12.03 13:37:46 [Server] INFO at java.net.AbstractPlainSocketImpl.accept(Unknown Source)
12.03 13:37:46 [Server] INFO at java.net.PlainSocketImpl.socketAccept(Native Method)
12.03 13:37:46 [Server] INFO java.net.SocketException: Socket closed
12.03 13:37:46 [Server] INFO Saving chunks for level 'LegendofKorra'/Overworld
12.03 13:37:46 [Server] INFO Saving worlds

Also on singleplayer, it works fine.