SIms 3 crashes after i move in a household?

Hello,
I just downloaded all my sims 3 games onto my new windows 7 computer. they worked fine on my windows vista computer. the graphic are much better and the game runs a lot faster than it did on my vista computer BUT, after I create a household I try to move them in and once live mode starts the games crashes and shuts down. please give me a solution to this terrible problem.