I have a couple games where this happened though they're both PS1 games.

My current copy of Mega Man Legends 2 freezes at certain points but once you get to Bola (one of the early bosses) it's pretty much screwed and won't play even in a PS3. The game is pretty beat up but that's because the previous owner mishandled it.

My copy of Crash Team Racing played fine up until about 2 years ago, and now even though there's hardly any scratches on it, sometimes it'll freeze out of the blue. I had to resort to using codes to unlock everything again because it kept freezing during Adventure mode. =/

It mostly plays fine in my PS3 though.