I have a 24 inch iMac that is a little over a year old. It is running the current OSX with all updates but today it started screwing up out of the blue and rebooted it's self. The first time it happened the machine kept trying to reboot several times but wouldn't fully reboot. It would then try to reboot again. I finally got it to boot up completely but then the machine froze up forcing me to do a hard boot via the power switch. Now it boot's to a white screen for about 30 seconds, then goes to the white screen with the Apple logo and stops. I tried to do a safe boot but couldn't get it to boot that way either. Anyone have any ideas? I'm new to apples and don't know much on trouble shooting them.