Was it a duplicate?
Interesting.
I am using Windows 8.1 and I have never had this bug before, it is probably your computer.
If it is the game, Notch might have coded it to not work properly with Windows 8 because "he hated it".
But i'm not going to point fingers at anyone until I see more people have the same issue.
Oh, I just realized that the latest snapshot was released today. This happened last night and I couldn't post the full log. It was too long.
EDIT: But whats weird is that I couldn't launch the game like it was trying to re-install itself.
This was on the latest snapshot.
Ok, thanks for telling me this.
If this is intended for lava to flow like water, Mojang must be trolling us.