Multi colored Games for PS2??

[Goodie]

I have noticed that with my playstation 2 games...some of them have a purple bottom to them,(similar to that of PS1 games which are black) and others are clear regular cd bottoms. When trying to backup PS2 games only the purple ones will read in my computer. The ones with the non purple bottom will not even read in my computer. CD clone always says that the drive is not ready. CDRWIN will not acknoledge that there is a cd in the drive either. This makes it impossible for me to backup my games or make an image file of them. Does anyone know how to fix this problem.