Wrong on the CD-Rs: I've seen them fail before, due simply to age. It happens with the cheap ones; the "archival quality" ones really do seem to be much better

Wrong on the CD-Rs: I've seen them fail before, due simply to age. It happens with the cheap ones; the "archival quality" ones really do seem to be much better, but I have some ~15 year old cheapies that are dead. You can even see on the disc that the dye has changed colors and is uneven. I've never seen a mass-produced CD (the aluminum kind) fail due to age rather than physical damage. However I have read about it happening, where the aluminum layer wasn't properly sealed in the polycarbonate and over time got corroded.