Game crashes after i get onto a horse, and wont let me go back into that world/server

Put the summary of the bug you're having here

What I expected to happen was...:
Describe what you thought should happen here I should of got onto the horse and NOT CRASHED

What actually happened was...:
Describe what happened here I got on a horse on a server and the game crashed, i tried logging back onto the server and the game crashed before the world loads.

Steps to Reproduce:
1. See Horse
2. ...Get on horse
3. ...Game Crash
4. ... Re launch
5. ..go back into world
6. Repeat 3-5