I bought a used 80gb, 4 usb, backwards compatible ps3. Blue Ray works awesome all updates done, PS2 games-no problem. But when I start playing PS3 games strange things happen, for example when I play Metal Gear particular objects shake or are slightly out of place. It is always the same objects doing the same things.Sometimes the colors are slightly out of whack. After about an hour and a half it freezes, but starts right back up.Yet when I play games like Resistance 2 that use less memory, it plays ALMOST flawlessly. Also, when I download a demo, it downloads fine, but wil not install.I did all the reformatting many times,changed the hard drive, reinstalled the games, tore it apart and cleaned it andtalked to sony. The wont take it because I bought it used, and don’t have a complete ID# sticker on it. It is definetely not the games, I tried many, or an overheating issue because it happens at start up. I cannot find anyone online with similiar problems. Any Ideas?