Burning a CD

I recently made copies of several hard to find CD's (Lyrita Label) loaned by a friend using my home computer CD burner. I have noticed over a several month period that the recordings seem to be degrading; I am getting a jittering sound. I am using what I think are decent CD's (Imation), and wondered if this is a common problem and what it's cause might be. I am pretty sure it is not my CD player as all commercially made recordings are playing flawlessly. In general I prefer to buy either new or used CD's so I have the liner notes etc, but sometimes that's not an option and I really would like to be able to do this without problems arising later when I no longer have access to that hard to find recordings. Any ideas of where to start.