I think the freezing depends on the game. I've certainly had a lot of freezes on NFSMW more than any other game I have. It froze a lot whenever you press B at the Safehouse, which normally will take you to the Menu. It froze once when I was racing

Like everyone mentioned here, it's very rare....it only happens once in a while, and sometimes more often for certain games.

I've had very little crashes, but NFSMW alone accounted for more than half of those ones, so it's more to the developer's coding than anything else...