Is the CD in reasonably good nick, or scratched and scuffed to billy-oh? It's worth your while to inspect the data surface with a glass for deposits as well as for scratches, and to wash it with tepid water and a little toilet soap. After carefully blotting the CD dry with a soft towel, let it dry completely for 5-10min. Then, on the offchance that the spectacles are at fault rather than the book, try the CD in one or more other optical drives. Older drives may have difficulty in reading HFS+ or higher-burn-rate discs, so try newer drives as well as your current old faithful. Injection-moulded CDs should not be subject to the same potential problems as burnt CDs, but a variety of drives may still be worthwhile trying if the data matter to you. There is also the possibility that the lens in an optical drive could use a cleaning.

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