When I logged in on 1 of my servers this morning. I had not had time to complete my base, so I made a small 2x2 box in the middle to log out. When I logged in, I jumped up to pick up 1 of the ceilings and here was an all mighty crash as my entire base, including all my forges and benches, all got destroyed.

I got annoyed so went to a different server. Made a bridge over a lake 2 x wide and around 120 long with large dino gates at either end. I saw an eternal bronto I wanted to tame but I didn't want to get hit while trying to tranq him, so I put 3 walls with a ceiling on it and 3 ladders to get up.
After dropping the bronto, i looked down at the ceiling I was stood on, which was only connected to the 1 wall on top of the 3, picked it up and I heard a breaking noise, crapped myself as I thought the lot was gone again, but no, it was the large dino gates at either that had broken.