Put the summary of the bug you're having here

What I expected to happen was I could just play normally and have fun and build.

What actually happened was I was in the air and I couldn't see the ground (the chunks were probably just loading.) but then it just crashes and I don't know what to do.

1. Create a new, superflat world with the only modification is setting the dirt to 52.
2. Load up the world.
3. Ta-Da!