Thanks for the suggestions. I actually accidentally discovered that if I go into Buy Mode and move a piece of furniture (this being the case of an overhead light) and then just move it back to its original location that fixes the Invisible Home bug. Kinda like Pescado's idea but way easier.
I run into another problem rarely, but I don't want to get into it. I'm usually able to fix it out of sheer luck. Sims 3 is really such a poorly coded game...I can't believe EAxis released this piece of junk unto the masses. Even so, it's a piece of junk I love!