Certain chunks of my world are regenerated on logout. Specifically, the chunks I have noticed being regenerated are around the spawn. The seed used is 1739977025357619589, with large biomes. I have re-created the world and it doesn't have the same bug (So I assume it is a corruption with my world)

I have tried reinstalling minecraft, and I am not using any mods.

Here is a link for a download of my world, if it helps.
http://www.mediafire.com/?5pnzg5mu78b7qib