I was playing Minecraft today, 1.9 pre-release 5, with my one and only mod being TooManyItems.
I found a stronghold and made my way to the room with the portal to The End. After placing Eyes of Ender in all the portal blocks and entering The End, I walked around a bit, eventually making my way down a steep cliff. Once down there, I accidentally engaged an Enderman. He walked toward me and disappeared when I hit him with my sword. I didn't see him for another 30 seconds, so I thought he had fallen off the edge or something like that. Just as I was about to start making my way back up the cliff, I was hit by the aforementioned Enderman, from the front. Somehow, I was knocked into the cliff behind me and began taking suffocation damage. I then managed to move out of the cliff, but I was floating in the air. My controls were also reversed; S moved me forward, W moved me backward, D moved me to the left, and A moved me to the left. The entire time I was moving around, I was floating in the air. I could even move back into the cliff out of which I had just come, causing me to continue taking suffocation damage. I eventually died from this, losing all my items and going back to the normal world, but I was still floating in the air. I exited the world and re-entered. Still floating. I quit the game and re-opened it. Not floating anymore, problems fixed (except for losing all my items, but whatever).
Has this happened to anyone else? (I apologize for the wall of text, but I felt the need to describe my problem in as much detail as possible.)