I'm not sure what is causing it. But every time I start a new game, (town level 0) a bunch of buildings just randomly start to complain of health until it gets to 0 percent.
I can progress though, by deleting the buildings, but I've never had this happen till now. No matter what difficulty
It might be that you have installed a plugin that allows level TTT residentials before you have acquired the infrastructure needed to make level TTT inhabitants happy.