You're PS2 is suffering from what many have dubbed DRE, or Disc Read Error. Basically, the lasers in the PS2 were shoddily made, and eventually, they'll stop reading discs. Certain formats might be affected first (In your case, DVD media is being affected. You should be able to play Blue PS2 discs, PS1 discs, and Audio CDs.) The surefire way to fix it is to replace the laser, but this is rather technical and requires opening up your PS2. There's also another fix where you strengthen the laser by turning voltage screws. This again requires opening the PS2, but there's many guides for this on the web. Probably the most temporary fix that might work is to clean the laser with one of those CD cleaner discs. This might work, but you may have to run it many times. I can only assume that this makes reading the discs as easy as possible for the laser. If this problem had happened earlier, you would have been able to take advantage of the settlement towards the class-action lawsuit they were charged with concerning this, where they would fix PS2s with this problem for free, despite warranty. I know I ended up doing this once, but I don't think that's in effect any longer. You might try there first.