Shadowy faces on Sims 2?

I know other people have posted this problem, but no one has been able to give a good answer. Sometimes while playing the game, I will save, an come back to find that whenever one of my sims interacts with something, the pop up face is dark and heavily shaded. And if I try to change their appearance, their icon at the bottom of the screen will also become shaded. Is there anyway to fix this without restarting the whole game?