Usually, one house looking like another is a cache issue. At least, it was a long time ago, when this first began happening. try getting rid of the 4 main cache files in the EA docs folder, as well as the World Caches folder.
Also, sometimes houses look broken like that ( even though they aren't ) if you've used Move Objects to place something.
On the rare occasions I use it, sometimes my houses look flattened out, or roofless in my test world, though they are perfectly fine when you actually enter them.