This happened to EVERY SINGLE house in Willow Creek for me. Even after rebuilding ALL of them, they disappeared again. Then I built another house for one family, played for a long time, saved, exited, and reloaded. The house was gone again. And the sims are never "compensated" for the lost objects with simoleons...
Could you post your Computer's DxDiag?
To gather a DxDiag on your computer, please follow the steps here: http://answers.ea.com/t5/The-Sims-3/HOW-TO-DxDiag-for-Sims-3-PC-Only/td-p/1049584/
You can attach the txt file to your post directly.
