Lots of noises in the shadow

Hi everyone! I just started to play around with Blender, and I ran into some issues. I am working on a Minecraft animation and there are a lot of noises inside shadow. I want to why it occurs and how to fix it. Thank you!


File for download: http://www.pasteall.org/blend/33371

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What renderer ?
What material settings ?
What lighting settings ?
What render settings ?

You haven’t supplied a demo blend file with your post that demonstrates the problem

Dunno how to upload a demo file, it won’t let me upload, I tried to pull the file into the window but nothing show up afterwards, can u help me?