I'm just adding my name to the list of gamers who have experienced this problem. I too am playing on a slim and it broke as soon as this achievement popped. Tried clearing my cache but nothing seems to fix it right now. I'm disappointed because up to this point I really liked this game...
Well I get up in the morning and I get my brief. I go out and stare at the world in complete disbelief. It's not righteous indignation that makes me complain. It's the fact that I always have to explain. - Van Morrison