I've come across several London multi-disc CDs where there is a thin pinkish foam pad on top of the CD. This foam pad deteriorates and sticks to the disc! If you have any of these I recommend you run, not walk, to your CD collection and check to see if any of your discs are infected. If you have this problem, I recommend you VERY gently try to pull or wipe the foam off while still in the case, vacuum the case with a brush attachment but still be very gentle. The information on the CD is on the top where the foam is stuck, it's easy to damage the data beyond repair. I suggest you rip it immediatly, I don't know if the foam that is still attached to the disc will continue to eat the disc. Spritzing some water on the disc may also help, but be gentle. Key word, gentle.