I am having problems with my ps2?

Certain games that are colored CDs(Example: Madden 2001 has a blue bottom, Twisted Metal 2 has a black bottom, The Sims has a blue bottom, etc.) do not work. When i insert it, the ps2 makes this terrible screeching and vibrating noise. It is an on and off occurrence but it has been happening more lately. I have the first generation ps2 that i bought in 2002. How can I fix this and do I have to buy a new ps2?