If the sound is fine when the source is not coming from the cd/dvd rom drive, then you can pretty much be sure that the problem lies in the cd/dvd rom drive itself. If your laptop is still under warranty, I would recommend getting it serviced and hopefully getting the drive replaced before it gets worse. There is a slight possibility that the soundcard is the problem, since MP3s are a lot slower bitrate than cds. You could test this possibility by saving some tracks from a CD as raw .WAV files and playing them back. If there is still no stuttering, then you can be sure it is a drive issue.