I've been playing the game quite frequently for the last week and I have not have any issues. I woke up and started playing this morning, and I played for about 15 minutes and then the game froze. So I restarted the game, and within 15 seconds the game freezes again. I repeated this 3 more times, with the same result, freezing after about 15 seconds.
I got desperate, so I'm reinstalling the game on my PS3 right now.