It appears that the server does not like the size of the player file that is logging in. Which is a little strange since it provides a location. I've seen that usually when it is a character that throws minecraft it usually does not have a location. If you are not the server admin have the admin copy the kcosttela.dat file (name of the ticking player) off the server and back it up. Then see if the kcosttela can log in. If they can then ask the admin to refund the lost items. Note that this might also make the player loose their research and/or waypoints. I'm not sure of anyway to save those without editing the kcosttela.dat file and I'm not sure what needs to be edited, sorry. Good luck.
Edit: If another player can get on the server have them test out and see what is at those coordinates. Please use a sacrificial lamb though as it might cause the new player to start ticking as well. Or use MCEdit if you can get it on the server or download the map.
