Originally Posted by alexh
Whenever I've come across disks that appear not to work it has always turned out to be the drive is broken and in some cases the faulty drive has turned out to be responsible for damaging the disks.
Always test your drive is working well with some unimportant known good disks for a while, take a look under the shutter for signs of damage or ware.
^^^^^This +1. +1 again. And then + another 1.
Seems to be worse with PCs, but I have seen this with Amiga, too. Drives fail.