CD player plays some CDs, not others.

I need a little advice here. My Denon player (8 years old) will play most CDs just fine, but now and then certain CDs, which played just fine before, will no longer play. The display reads Track 01, and that is all. I can skip to track 02 but it still will not play. If I put in another CD, it will play. Then if I go back to the other CD, it will not read the CD. These are CDs that will play in my Sony Walkman, but for some reason my Denon is not able to read them anymore. They are in good shape, clean, and had played in the past. Is the laser shot?? Need a new player?? ALong those lines, what quality can I get in the $500-$600 range, single play or changer. I like Denon, but will try any other recommended to me. Thanks in advance. Al on Cape Cod