My computer is no longer able to view two read-only data CDs. These CDs are 6-years and 3-months old respectively. Both CDs are in pristine condition (no scratches). I was able to read these CDs with no problems until now but they no longer work on any computer. I could not copy the older CD, but the copy that I made of the newer, showed the same problem of the original: some files are not read. Though not being able to copy it, I am able to read some files of the older CD; but hundreds of files are, simply, omitted, though I am sure that the files are on the disk. In addition, an odd popping sound is heard when reading the older CD. My understanding was that a CD should last some 200 years. I have many, many other CDs containing archival data, that are absolutely not replaceable.

Firstly, we should probably dispel a myth: CD-R disks do not last forever, they will degrade over time, even if they are kept under ideal conditions. Of course, bad treatment of the CD-R disks will accelerate the process of degradation. The length of time a CD-R disk will last significantly varies depending on the type and brand of disk you have purchased. For example, a $0.25 ‘no-name’ CD-R is probably a significantly less quality product than a brand name CD-R media which costs $1.00. Likewise, the poorer quality media will degrade faster. A good explanation of CD-R longevity can be found at www.cdrfaq.org/faq07.html#S7-5. As you will read in the article, some manufacturers boast their media will last for 200 years - but, again, this depends on the quality of the media and the way it has been handled.

Back to your specific question, as the problem occurs when reading the CDs on other computers it is obvious the problem is something with the CDs themselves. If you have used poor quality media for the CD which is 6-years old then I am not surprised you can no longer read that CD - and there probably isn’t much you can do about it. However, it may not be too late to recover data since the computer could read the disks until recently. We can try using a utility called IsoBuster. This is a data recovery tool for CDs and DVDs, which is part freeware and part shareware. If this program cannot recover the data from the CDs, it is unlikely that there are many other alternatives you could try. You can download IsoBuster from www.smart-projects.net/isobuster/. If this works, please let me know as I am interested to hear the outcome. I then suggest you buy some good quality CD-R media (possibly a different brand to the previously used media) and write the data to the CD.