I'm about to head for some sleep, but if you upload your world then Josh or Keith or I can fix it for you.
Actually, you may not even need to do that. This may work:
1. First update to the latest version of the game.
2. Then open up the game where you are in the bad chunk. Hit F3. You'll see some debug info, along with a chunkID and regionID near the bottom. Note these down.
3. Close the game. This is important, otherwise the next step won't work.
4. Then look inside your RuntimeData/Worlds folder and the world folder for your specific world in question.
5. Probably it's a good idea to make a copy of this folder before you proceed further, just in case.
6. Now go into the subfolder with the number matching the regionID you wrote down earlier.
7. Now look for the Chunk.datc file with the number matching the chunkID you wrote down earlier. Delete this file.
8. Restart the game, and the chunk will be regenerated.
9. If this was a bug we already fixed (which I think it is), then it will generate correctly and you can proceed normally. If this isn't a bug we already fixed, we'll need a copy of your world folder so that we can duplicate the bug, then fix it, then hand you the fixed one back.
Sorry for the trouble! Hope that helps.
