World of Warcraft Issues. Certain Toon Won't Play?

For some reason my toon, Paladin lvl 66, won't play. Everytime I try to log onto it either it auto disconnects me from the server, or it freezes at the loading screen which causes me to restart the client. All my other toons work fine, except my main one. I'm getting very sick and tired of the bs. I have already gotten istance from Gms before. Please Help!