I had this same problem but most of the ppl are rite about the overheating or the harddrive failing. but after clean my ps3 with the (Can of Air) its not blowing hard anymore ^-^ many thinx. and still i have the same problem when it turns off every 3/10seconds now something is telling me its my harddrive that is cause it to turn off so i call my friend over my house ask him to get his harddrive(NOT HIS PS3 HARD DRIVE) after he showed up we when to the (system settings) after go to BACKUP Utility usually take like 56mins to backup and when that done i go to format ulitity and i use quick format took like 1hr 56mins that deleted all my save data and etc but i had reset up my ps3 all over. for some reason my ps3 dont turn off by itself anymore which it most of been my save file that mess up my ps3 after that beening done i played modnation racers for the first time and when i create a character it turns my ps3 off again but this only happen on MODNATION Racers Character create all the other games i played are fine!!! i can race,create my ride but not character plz i need help and i dont understand why it happen on modnation racers only!! but the only i can do is just to edit my character and just play the career mode.