Audio cd problem

I have a problem with older cds, some not very old. The fuzziness or static sound is near the end of the disc, sometimes several songs. I ripped to the hard drive, it was still there in the last 4 songs. I copied the disc and it wasn’t present in a few songs so I gained some. I have a Samsung & an Asus dvd writers, both less than a year old, but it has happened on Plextor, Lite-On, and other burners. It seems to be bad cds. I’ve copied a lot of cds and sold the originals and now I’m worried that I’ll lose the music. Its already happened to a lot of cds, some with paper labels, some without, some blue, some silver. I don’t know what to do and I’ve been looking around CD Freaks for an answer. I know cds aren’t forever, but I thought ten years or so was at least the minimum.