hi guys my mba 2.13 ghz 2g ram 128 ssd is shutting down on its own. i am running up to date 10.6.7. every few seconds it asks " are you sure you want to shut down", the same dialog box that would come up if you held the power button down. very strange. i tried to reinstall but the comp was still shutting down (without dialog box) no applecare. any ideas ?