The sims 2 problem of mine?

Check the back of the disc for any scratches or fingerprints. If there are then clean them off...I had the same problem at first but then I took it out to blow on it and then I put it back in and it worked. Sims 2 can be strange sometimes....( I bought a game and it didn't work and I had to return it -_- ) Hope I helped. :D