Dell LATITUDE D400 - Manual (Page 92)

If you notice problems, such as skipping, with the playback quality of your CDs or DVDs, try cleaning the discs.
1. Hold the disc by its outer edge. You can also touch the inside edge of the center hole.
NOTICE: To prevent damaging the surface, do not wipe in a circular motion around the disc.
2. With a soft, lint-free cloth, gently wipe the bottom of the disc (the unlabeled side) in a straight line from the center to
the outer edge of the disc.
You can also purchase commercial products that clean discs and provide some protection from dust, fingerprints, and
scratches. Cleaning products for CDs are safe to use on DVDs.
3. Connect your computer and devices to electrical outlets, and turn them on.