Everytime I join my friends server, I start to fall off the map and I dont see anything, but this is only hapen to me, not my friends.

Put the summary of the bug you're having here

What I expected to happen was...:
I would load into a server and start playing Minecraft as usual

What actually happened was...:
Nothing happened and I was falling down the void about 100 blocks a second

Steps to Reproduce:
1. just log on and play Minecraft multiplayer
2. ...
3. ...