Hi! My Mackook 13", the model after 2008. just decided to stop working today... Any time you boot the computer you can hear the chime (hardware test), grey screen appears, apple logo appears and then off... That happened for the first time when using it and the cursor stop responding to the trackpad so decided to shutdown and restart and since then always as soon as apple logo screen appears it will always shut down. My troubleshooting consisted in: Reset SMC, SMC resets ok, but same problem PRAM Reset, but it doesn't re-start while pressing the keys so cannot hear the chime second time. And after that still no progress First though on HD problems so try the following: Tried DiskWarrior DVD and shuts down at same apple logo screen Tried to load Mac Os from bootable USB to see if I can use the Disk Utility, after I select the USB on the initial grey screen, when holding option key, the grey screen with the logo appears and shuts down Tried Option key to start recovery partition and guess what? got same after selecting the partition logo appears and system shuts down Tried Verbose mode and after the whole test shuts down (you can see the screenshot just before it shuts down) Tried Comand (⌘)-S and the same once again Pulled out HD and tried as external HD to my computer and work just fine, tried DiskWarrior on it and everything is good, then put it again on the macbook and same shut down again. Any clue? Thanks!