The Sims3 : How to fix CRC error ??

I bought the sims 3 that has 1&2 dvd. I enter dics 1 and it's start to install. During the installation, they stop install and said  "CRC error" and give a choice to press "abort/retry/ignore". I just press ignore. And i'ts just continue  the install. After the installation done.I open the folder that said " U MUST READ THIS 1ST". the folder tell me that i have "when the installation become the message "CRC Error", just click "Ignore" to continue the installation, after install The Sims 3, then use Disc 2 crack file to replace the CRC Error file. When they ask u to replace the file, just click replace, after that u can start to play The Sims 3." and i can't understand what i have to replace ?? Please help me....