Pleasantly, I discovered an audio CD which I had given up for lost, but which had just been put back in the wrong case. Not so pleasant was the fact that a nasty little proportion of the back-up CDs had errors.

No key data was lost -- just personal stuff from many years ago which happens to be backed up onto tape (I think) -- but it was a timely prod about the reliability of certain types of recorded media.

Then I read in ComputerWorld that an IBM storage expert reckons that some types of burned CDs will only last for two to five years. Interestingly I found that the very old back-up CDs I burned over ten years ago were fine, but that the few that were not were about five years old.

One of the possible reasons for that is the older batch were burned at 2x in my old trusty HP recorder (which has since gone to the great CD burning vault in the sky) but that the newer ones were recorded at whatever the drive could handle -- 20x, 32x and sometimes 48x.

Kurt Gerecke, the aforementioned storage expert, says that, unlike pressed original CDs: 'Burned CDs have a relatively short life span of between two to five years, depending on the quality of the CD. There are a few things you can do to extend the life of a burned CD, like keeping the disc in a cool, dark, space, but not a whole lot more.'