Why does car CD player sometimes eject cds instead of playing them? Then sometimes play them?

We have a '96 Grand Cherokee. The CD player has gotten to where it, most of the time, won't play cds. Instead, it just kicks them back out. Every now and then it will play cd, but still, it will skip. It's very seldom that a cd will play without any problem. Is there anything that " I " can do to fix this problem?