A defect in the CD can cause imperfect copies. For example a scratch on the surface of the disc or a defect to the actual information under the surface could cause a copy to be just about readable on one player but unreadable on another. I must stress though, that what I'm suggesting is not pure black or white; in other words, we probably couldn't prove this once and for all.
My suggestion about making a new copy is that:
- pure chance means that the new copy may be better than the previous one
- changing the format of the copy will mean that the copy is written onto your computer, and subsequently read by iTunes, differently to the previous copy - and hopefully the defect is not obvious on the new copy
There is something else you could try; go into iTunes' Settings and turn on the error correction. What that does is slow down the copying process, which allows the CD reader to make sure it's got a better copy. You could then make the new copy in the same format as the original. Go to Settings/General>Import Settings>Use error correction when reading Audio CDs.
Note that this only works for Audio CDs, it will not work on files already on your computer that you import to iTunes via File/Add File to Library or with data CDs containing audio files.
