TO FIX THIS ISSUE YOU NEED TO DO THE FOLLOWING.
Redownloading the game will not work, Nor will scanning of his or her files. This has to be done by a server admin who has ftp access.
Find out the persons Steam ID who is having this issue on the specific server.
Once you have the Steam ID of the person, Find their steam ID folder under the folder location: /save/myserverdata/userdata
Inside the userdata should be folders of the steamID of that user delete it. it will fix his problems and allow him to log back in.
It will also wipe all learned recipes, the inventory and all equipped weapons/items.