As I understand it, this is a result of a corrupted save file, caused by problems or interruptions of any sort while closing the game or switching tribes.

This is a blessing to some people though - Puzzles only last so long, and are rather easy to complete, with the requisite knowledge. Your tech remains, so finishing enough huts to support your population should be easy. Having skilled villagers, and knowing how to restore the alchemy lab and what potions to use, re-securing your food supply should be easy, too. I personally like this glitch, as it gives an established village a little more game time.