Just got myself a fat PS2. I have only one game so far, Fifa05 and it stops loading in middle of intro - it just stays there forever, no error or something. But I've tried playing DVD movies and Audio CD's of all kind (copies, original movies and ones recorded on my standalone DVD recorder, all kinds of media - silver, blue) and it played them all. Is there chance that it is just matter of faulty disc with Fifa05 or it could be that PS2 is toasted?
It could be the lens problem inside the PS2. Unless the game is burned, then that's a whole different story. But for a legit copy of Fifa that doesn't seem to work well, either the disc is wrecked, or it's the PS2's lens.
I'd say just a bad CD. PS2 seems fine if it plays everything but that. Try making an ISO of the game through a computer, your bound to get read errors through the way.