Server crashes when one specific user joins?

When one user joins, there appears to be a chunk error and the whole server crashes. He tells me he is using a freshly installed 1.7.10 vanilla client and people with the same configuration (including myself) don't cause issues. When he crashes the server, everyone gets timeout errors when they try to connect and there is an error on the console, but the server doesn't appear to completely go down. Here is a copy of an error log. Again there are no problems with anyone other than this one person.

This is a bukkit 1.7.10 server. A few basic plugins (worldedit, restore sponge, nonop gamemode change). Online mode, not cracked. Any idea how to fix this? I attached a crash log.

 

Go in to server's root directory, go to the default world's folder, go to playerdata, delete their UUID.dat file. You don't have to restart/stop server. You can find the player's UUID at http://mcuuid.net/

 

oceantheskatr: That fixed the problem, thank you.

 

You're welcome