I've made a back-up of a scratched original, that had errors when trying to make an ISO, and it only froze on me once from the hours I've played it. I've already beat the game.
It seems like you have a bad-burn, clean your original and make sure it has no major scratchs.
Do you get any errors when trying to make an ISO?
Make sure ignore errors is off.
You don't need a patch for NFSU.