reliability of dvd+rw

Hi, I thought I'd share with the list the problems of using +rw as an archive medium. Disks I've written about 6 months ago seem to have problems reading. Also even if you just mount media read only the seem to suffer from the laser reading and can degrade whist you use them, e.g. reading a part of the disk repeatedly causes the disk to fail at that point. I might just be very unlucky but this seems true for a few types of media I own. -- M