Problem: horrible distortions of the Sim Pets. No problem with Sim games before. What do?

Just got the Sims 3 Pets. Installation went perfectly fine. No other problems with my Sim Games before this. Went into create a family, started to make pets, BOOM pet sim explosion. I'm sure you all know what I'm talking about, features greatly distorted etc. I am wondering how to fix it. If it's just the disc or what.