Today I went to play a self-made cdr which was previously playable but now just a rhythmic noise from my cd player. My laptop reads it as bank disc, my pc spins it but no sound. I remember the horror stories about the limited life of cds/cdrs but this took me by surprise. The disc looks fine, no visible defects. Not sure when I made this disc but ten years ago at least. And I didn't make a copy! It was a recording of a concert I attended which makes the loss worse.
Moral, I guess, make a copy of essential stuff.