Hello, I am in the process of backing up my data for the year. But I was disappointed very badly when I found that some increamental backup sets on a CD can not be read anymore. I am an average careful person and I take reasonable care of my CDs. But how could this happen? I mean, how I could have done better to make all my CDs at least readable when I want them? Here are some clues on what happened to this particular problematic CD. It is stack on another CD in a case. The surface some how got dirty or scratched. I don't know if it is my CD drive to blame or the other CD underneath in the case. But I rarely move these CDs. Why it still got scratched? I just don't know why. Is it some kind of physical or chemical reaction happened? Maybe from now on, I shall always make two copies and put them in one box each separately, one under another CD and one on top of another CD. This way I still can keep four CDs in two cases. I also checked the status of all my CDs. Some of them are shining like new. Some of them already have scratches and perhaps dirt on them. I don't know how differently I treat them. This is really bad, boy. Some day, some of them cannot be read again when I want them. purely sad, apparently no nothing I can do now to protect my data. Any rescue measures can save those can not be read? Can I use water to wash the CDs? But how can I make or get those special spot-less water in car wash? Shall I use a dryer to dry washed CD? Can I ever get this problem solved and run zero risk of losing data?