I'm having the same issue, the game worked fine yesterday. I'd started building a house, it's actually just fencing, then I came back on today to finish building it, but when I try clicking on build mode it says, it can only be done in world editor. I can go into world editor and design a house, but I don't know what will happen if I want to buy my sims new furniture.
I've saved my game under a different name in the hope it's preserve my sims and everything I've done, just in case something eles happens.
