I've got a friend with a slim PS2 that seems to be having some weird issues.
She puts in her games(God of War, Vice City) and the games won't work. No scratches or damage to them whatsoever. She puts in her boyfriend's game(Frogger) which is scratched, and everything works just fine. I tried to figure it out on my own, but I think I had a small aneurysm. lol.