Ok, let me start off by mentioning this:
If your simply READING the disk and it becomes damaged, the heads of the drive are magnetized and they need demagnetized. Same thing happens with Cassette decks we all used to know and love, some still do.
If your trying to write the disk and it ruins it, its probably because its mis-aligned.
Main PC: Intel core I7 920, MSI x58 platinum, Radeon4850
PB: tibook G4, ibook G4, Lombard, 160, 165, 180, Duo 2300x2, Duo 270c x2, 520cPPC, 3400c, 1400c
Desktop: G3AIO, 5260/100 x2, SE, SE/30, 512k, plus, LCIII, 7100, iMac G5 iSight, 6400/225