Red Dead Redemption freezing up?

Okay so I got rdr when it came out and it plays fine on my ps3. My girlfriend just bought a ps3 so I let her borrow it and it is continually freezing. Most of the times at the start up loading screen. It's not the console because shes been playing other games and they are working fine. Just to check i put rdr in my ps3 and it doesnt freeze. So im lost. Anyone know what the problem is?