Have you tried resetSim? How about a game restart?
Resetsim didn't work. Reloading the same game without saving didn't work either.
All I can do is relie on my backup save file, which isn't far behind what I was actually doing, and I am really glad I have one save file for towns and one for vacation now.
I leave this topic open, for in case someone else has this problem as well.
The thing is, it happend after I have send my sim on vacation to finish his book while I just before has switched his vacation home with another home with the same name.
I am saying this because it might have something to do with it.