Andrew k
Comments
You may need to delete mods if you have any, you can also try to reinstall graphics card drivers, install java, or try deleting the logs folder in %appdata%/.minecraft
In the new snapshot 13w21 there is a bug where if you haven't tamed a horse yet you can still put a saddle on it using the inventory. The horse acts as if it is tamed. When the saddle is removed however the horse becomes unfriendly and will try to kick you off again.
no