Sims Pets not showing + Sims 3 is runnig very slow/freezes

Ok so I installed The Sims 3 + all expansions except Fast Lane) I followed all the steps from the main page forum on how to install the Sims 3 correctly...everything installed smoothly except for the Sims Pets which gave an error message saying that some files did not match the origin files so I clicked ignore and installed anyways. So after all was installed I downloaded the ultimate fix. I do not know if it makes a difference but was I supposed to apply the cracks from the ultimate fix to the expansions? On the Main forum it says not to install any cracks but it also said to download the ultimate fix which confused me...Please help! I unistalled everything and was going to start over with some help...since the game played slow and the Sims 3 Pets were not working

//EDIT

Im getting a CRC error message (Sims Pets) saying that the cache doesn't match the files in the setup's cab file

//MOVED
Hello,

You should not use any crack files that come with the downloads, only use the updated, working crack that comes with the Ultimate Fix, exactly as described HERE.

As for the CRC error, try this:

Open the .rar file you downloaded using only WinRar, which can be downloaded from www.games4theworld.org . (If you use any other software than WinRar, like WinZip or 7-zip, the files will get messed up!)
When you've opened the file using WinRar, select áll the files in it and drag & drop them to a folder on your Desktop. When the extraction is done, close the .rar file and open the folder on your Desktop. Now, start by reading the included "# Installation Guide.txt" and you should be able to get the game to work yourself. Good luck!