Crash after Creating new World (Singleplayer)

What I expected to happen was...:
Creating a new world in singleplayer modus.

What actually happened was...:
After clicking on "Create New World" I just see a "Loding World" for 3 to 5 seconds and then a crash report is shown.

Steps to Reproduce:
1. Click "Singleplayer"
2. Click "Create New World"
3. Click "Create New World"

4. Crash!