Almost every Rockstar game has problems overheating the PS3. They have memory leaks... put your PS3 on a hotplate Should be ok after that...

Actually I would recommend everyone doing that, an elevated hotplate that is. It lets the PS3 vent much easier and its also in a more accessible position for when you vacuum out the dust on the vents

Hard to find a pic of what I was takling about, the hotplate I use is more metallic and raises the PS3 a lot more than this one, but I think something like this would get the job done too:


Or maybe something like this lol: