Let me guess, you have a stat of the art ATI graphics card and you are shocked by the corrupted or transparent geometries in “The Sims3” specially the characters hair.
The reason is a malfunction in your graphics card’s “Adaptive anti-aliasing “. Open Catalyst control center and disable “Adaptive anti-aliasing”.
This same features caused a similar problem with Velvet assassin that I discussed before .
You can also read about the ATI driver and some of my thoughts about it here