Dvd-r discoloration causing read problems

Hi i have these generic DVD’s ive been using for DivX movies, and they are discoloring like hell, its causing read problems on some of my dvds (crc errors)

i dont know whats going on, i took a picture with my phone to compare a normal colored disc (left) to a heavier used disc (right)

maybe its because the dvds are spinning for so long for 2 hr+ movies and the rom heats up and causes the discoloration?
my dvd rom is a LG GSA-4120B DVD-RAM and the dvds are some generic brand with and i think are the type u can use a disc printer with, thanks

put a post in the Media forum. maybe someone there will know what is going on. my guess is that cheap media use cheap dye etc and that soon those dvds will no longer be playable