Sims 2 Pets Stories Error?

I just installed Sims 2 Pets Stories on my laptop, and the on the case it says laptop friendly, but I've played it for about an hour, and a lot of the time there are like Sim glitches. Sometimes my Sims head is unattached to my Sims body and my Sims body is all stretched out and fat and half way across the room! At one point, at the end of my playing time, my dog and my Sims body had patches of black all over it and it's getting annoying having to play like this. Can anyone tell my why my Sims are all goofy???