Thats kinda weird because usually the PS2 has rouble reading blue bottomed disks. It should read the white bottomed disks just fine. Make sure that their are no lethal scratches on the disk. Just clean the laser. It should tell you in this link.
http://www.neoseeker.com/Articles/Ha...Guides/ps2diy/
If you see in the pics that he takes the laser and CD tray out don't do that. Just clean the laser while it is inside the case. And your PS2 will probably not look the same anyways.