Try going to my documents EA and delete the sims 2 folder. After deleting it restart the sims using your seasons disk. It will creat a new sims 2 folder and things should work. Always run the game with your latest expansion.
You should download some patches as well at http://www.thesims2.ea.com/update/ I don't think they'll solve your problem but they can help you with your future simming. They are really good if your game is all glitchy and buggy.
