Looks like something wrong happened when downloading the patch... Here's what I want you to do:
(Back up your saves before you follow my directions. If you don't know how, the steps are in the instructions, but I'm not responsible if there's a mistake.)
Download a new client from the Minecraft website. Then, I want you to follow these directions:
Windows 7:
- Press start, type in %appdata% in the search bar, and press enter. A folder should pop up.
- Navigate your way to .minecraft/saves/. Copy everything in that folder to another location. Your desktop, for instance.
- Now, go back up the folders and delete the .minecraft folder. Empty your recycle bin.
- Open up the Minecraft Launcher and log in. If you followed directions correctly, it should automatically update.
- Now, close Minecraft and copy the stuff you copied to your desktop back into .minecraft/saves/
Open Minecraft. Enjoy!
Windows XP:
- Press start, click "run...", type in %appdata% in the run dialog, and press enter. A folder should pop up.
- Navigate your way to .minecraft/saves/. Copy everything in that folder to another location. Your desktop, for instance.
- Now, go back up the folders and delete the .minecraft folder. Empty your recycle bin.
- Open up the Minecraft Launcher and log in. If you followed directions correctly, it should automatically update.
- Now, close Minecraft and copy the stuff you copied to your desktop back into .minecraft/saves/
- Open Minecraft. Enjoy!
This should give you a fresh install of Minecraft, and allow it to redownload the files that were corrupt. If it doesn't help, check your internet connection for packet loss, and try the steps again.